Process for producing polymers or oligomers of controlled molecular weight and end group functionalities

ABSTRACT

A process for the production of polymers by free radical polymerization, characterized in that there is added to the polymerization system one or more compounds of general formula (A), where R 1  is a group capable of activating the vinylic carbon towards free radical addition; Y is OR 2 , where R 2  is an optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, or optionally substituted saturated or unsaturated carbocyclic or heterocyclic ring; X is an element other than carbon selected from the Groups, IV, V, VI or VII of the Periodic Table or a group consisting of an element selected from the Groups IV, V, or VI to which is attached one or more oxygen atoms; and n is a number from 0 to 3, such that the valency of the group X is satisfied and, when n is greater than 1, the groups represented by R 2  are identical or different.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-part of application Ser. No.08/475,329 filed Jun. 7, 1995, now abandoned which is a Divisional ofapplication Ser. No. 08/325,496, filed October 19, 1994, now abandoned;which is a Divisional of application Ser. No. 08/072,687, filed Jun. 7,1993, now U.S. Pat. No. 5,385,996, issued Jan. 31, 1995; which is aContinuation of application Ser. No. 07731,393, filed Jul. 17, 1991, nowabandoned; which is a Continuation of application Ser. No. 07/372,357,filed Jun. 5, 1989, now abandoned.

The invention relates to processes for radical-initiated polymerizationof unsaturated species and for the control of molecular weight andend-group functionality of the polymeric products produced from suchprocesses. Polymers of limited molecular weights, or oligomers, areuseful as precursors in the manufacture of other polymeric materials andas additives in plastics, elastomerics, and surface-coatingcompositions, as well as being useful in their own right in manyapplications.

In conventional polymerization practice, the manufacture of oligomersrequires the use of an initiator which acts as a free radical source,and of a chain transfer agent. The chain transfer agent controls themolecular weight of the polymer molecule by reacting with thepropagating polymer radical to terminate its growth. It then initiates anew polymer chain thus transferring the growth process from one discretepolymer molecule to another discrete polgoleule. At least a part of thechain transfer agent is incorporated into the polymer molecule and thusis consumed during the process. The incorporated residue of the chaintransfer agent can lead to undesirable end-groups on the polymer.

The chain transfer agents most commonly used are alkanethiols, whichpossess an objectionable odour, lead to a wide distribution of molecularweight with certain monomers, do not allow the production of telechelicpolymers, and offer limited scope for the preparation of polymers with asingle functional end-group. Additionally, with thiols there is littlescope for the chain transfer efficiency to be optimized for a particularpolymerization.

The present invention provides a process for the production of lowermolecular weight polymers by free radical polymerization, which processis characterized by the addition of compounds of the general Formula Ato the polymerization system. The process can, by appropriate selectionof the compound of Formula A, produce polymers with groups capable offurther chemical reaction at one or both ends of the polymer chain.

In Formula A, R¹ can be hydrogen, but preferably represents a groupcapable of activating the vinylic carbon towards free radical addition.Suitable groups are phenyl and optionally substituted cast aromaticgroups, alkoxycarbonyl or aryloxycarbonyl (—COOR), carboxy (—COOH),acyloxy (—O₂CR), carbamoyl (—CONR₂) and cyano (—CN); AND

Y is —CH₂X(R²)_(n) or —OR²;

WHERE

R² represents optionally substituted alkyl, optionally substitutedalkenyl, optionally substituted alkynyl, or optionally substitutedsaturated, unsaturated, or aromatic carbocyclic or heterocyclic ring;AND

when Y is —CH₂X(R²)_(n), X represents an element other than carbonselected from groups IV, V, VI, or VII of the Periodic Table or a groupconsisting of an element selected from groups IV, V, or VI to which isattached one or more oxygen atoms. Suitable elements X include sulphur,silicon, selenium, phosphorus, bromine, chlorine, and tin. Examples ofoxygen containing groups include phosphonates, sulphoxides, sulphones,and phosphine oxides; AND

n is a number from 0 to 3, such that the valency of the group X issatisfied. When n is greater than 1, the groups represented by R² may beidentical or different.

In Formula A, substituted rings may have a reactive substituent groupdirectly or indirectly attached to the ring by means of a methylenegroup or other side-chain.

The reactive substituent groups referred to above for R¹ and/or R² inFormula A do not take part in the actual lowering of the molecularweight, but are installed at the ends of the polymer chains and may becapable of subsequent chemical reaction. The low molecular weightpolymer containing said reactive group or groups is thereby able toundergo further chemical transformation, such as being joined withanother polymer chain as described subsequently in this specification.Suitable reactive substituents include: hydroxy (—OH); amino (—NH₂);halogen; phosphonate; trialkyoxysilyl; allyl; cyano (—CN); epoxy; andcarboxylic acid (—COOH) and its derivatives, such as ester (—COOAlkyl).The substituents may alternatively be non-reactive such as alkoxy(—OAlkyl) or alkyl.

Alkyl groups referred to in this specification may contain from 1 to 32carbon atoms. Alkenyl and alkynyl groups may contain from 2 to 32 carbonatoms. Saturated, unsaturated, or aromatic carbocyclic or heterocyclicrings may contain from 3 to 14 atoms.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE shows the reaction mechanism by which the free-radicalpolymerization process of this invention controls polymerization. In thedepicted schema, the marked oxygen group on either side of the lastarrow on the page indicates where the oxygen group is located before thefinal polymerization step, 0 to the end-group, and where it is locatedin the final polymer, as the end-group.

The process of this invention uses the compounds of general Formula A asalternatives to thiols or other chain transfer agents for the control ofmolecular weight. The process of this invention may be operated in asimilar manner to conventional processes using thiols. For example, theprocess described herein is applicable to the manufacture of syntheticrubbers and other polymer formulations, where reduced molecular weightaids processing and improves properties. The process can also be used toproduce low molecular weight polymers and oligomers for a variety ofapplications, such as high-solids surface coatings, paints, andadhesives. For example, low molecular weight hydroxyacrylic polymers canbe prepared using the compounds described in this invention and thesecan be later crosslinked by reaction with polyisocyanates.

Compounds of the general Formula A have the advantage of being simplyprepared from inexpensive starting materials. Unlike thiols, they donot, in general, possess an objectionable odour. They exhibit anunexpectedly high activity in controlling molecular weight inpolymerization reactions and are superior to thiols. Their activity issuch that their chain transfer constants approach the optimum of 1.0 andthis activity is not highly dependent, as it is with thiols, on thestructure of the propagating radical. As is well known in the art,compounds with chain transfer constants close to this optimum of 1.0allow the production under convenient conditions of polymers of narrowmolecular weight distribution. Additionally, when the chain transferconstant of a given compound with two or more monomers is reasonablyclose to 1, the distribution of molecular weights in copolymerizationsof these monomers can more readily be controlled. The compounds ofFormula A in general are superior to thiols inasmuch as their chaintransfer constants are closer to 1.0. Additionally, with this inventionthere is scope for the chain transfer efficiency to be optimized for aparticular polymerization by the appropriate choice of the substituentR¹ in Formula A. For example, when R¹ is electron deficient, theefficiency with electron donor monomers such as styrene is enhanced.

The process of this invention utilizing compounds of the general FormulaI [Formula A, Y=—CH₂X(R²)_(n)], unlike processes involving other chaintransfer agents, directly produces polymers or oligomers containing apolymerizable olefinic group at one end and can be used to preparemacromonomere, whiGh are useful materials for the preparation of graftcopolymers by methods well known to the art.

When the process utilizes compounds of Formula I containing a reactivesubstituent group on at least one of the groups R², it may be used toproduce polymers and oligomers with said reactive substituent on the endremote from the olefinic group. Polymers or oligamera with reactivesubstituents on one end may also be prepared when the process utilizescompounds of Formula I with reactive substituents on R¹ or when theprocess utilizes compounds of Formula II [Formula A, Y=—OR²], containingreactive substituents on either R¹ or R². In this latter case usingcompounds of Formula II, the resultant low molecular weight polymers oroligomers contain no double bonds and, therefore, do not have theproperties associated with a macromonomer. In a number of instances thisis desirable, for example, in processes which are taken to very highconversion.

Mono-end-functional polymers or oligomers, produced by the process ofthis invention, may be linked by means of the introduced reactivesubstituent directly to a polymer backbone leading to graft copolymers.They may also be linked with other end-functional polymers or oligomersto form AB block copolymers or with suitable telechelic polymers oroligomers to form ABA block copolymers. Block copolymers are importantas compatibilizing agents, adhesives, and in advanced-surface coatingformulations. Low molecular weight polymers and oligomers with onefunctional end-group may also possess desirable physical attributes intheir own right, such as surface wetting properties.

The functional substituents installed at one or both ends of the polymerchains by the process described herein may be converted into otherfunctional groups by performing chemical functional grouptransformations as is well known in the art. For example, esterfunctionality may be converted into carboxylic acid functionality byhydrolysis, tert-butyldimethylsilyloxy groups may be converted intohydroxy groups by treating the polymer with fluoride ion, andchloromethylphenyl groups may be treated with nucleophiles to afford avariety of other functional groups.

Mono-end-functional polymers or oligomers that do not contain a doublebond may also be converted to macromonomers by methods well known to theart. For example, —OH or —COOH terminated polymers can be prepared usingII in which R² carries hydroxyl or ester substituents. Thehydroxy-terminated polymers may then be converted to macromonomers byreaction with acryloyl or methacryloyl chloride or similar reagents. Inthe case of —COOR terminated polymers, macromonomers can be prepared byreaction with glycidyl methacrylate or similar compounds. Suchmacromonomers by virtue of their chemical structure have differingreactivity in polymerization reactions compared with those produceddirectly by the process utilizing I.

When the compounds of Formula A contain reactive substituents on both R¹and R², the process is particularly useful for the preparation oftelechelic or di-end-functional polymers and oligomers. These productsof the process are especially useful and have applications ascrosslinking agents to produce polymer networks and as building blocksfor the preparation of multicomponent polymer systems such as segmentedand ABA block copolymers. For example, α, ω-dihydroxy oligomers orpolymers can be reacted with the readily available α, ω-diisocyanatooligomers to produce segmented polyurethanes which are useful aselastomers and high impact strength materials for a range ofapplications.

The following compounds of Formula A are novel and form part of thisInvention:

α-(t-Butanethiomethyl)styrene

α-(n-Butanethiomethyl)styrene

α-(Carboxymethanethiomethyl)styrene

α-(Carboxyethanethiomethyl)styrene

α-(2-Hydroxyethanethiomethyl)styrene

α-(2-Aminoethanethiomethyl )styrene

α-[3-(Trimethoxysilyl)propanethiomethyl]styrene

α-(n-Butanesulphinylmethyl)styrene

Ethyl α-(t-Butanethiomethyl)acrylate

Ethyl α-(Carboxymethanethiomethyl)acrylate

α-(Carboxymethanethiomethyl)acrylic Acid

α-(Bromomethyl)acrylonitrile

α-(t-Butanethiomethyl)acrylonitrile

α-(Diethoxyphosphorylmethyl)styrene

α-(4-Methoxycarbonylbenzyloxy)styrene

α-Benzyloxy[4-(chloromethyl)styrene]

α-Benzyloxy[3-(chloromethyl)styrenel]

α-(4-Cyanobenzyloxy)styrene

α-[4-(Hydroxymethyl)benzyloxylstyrene]

α-[4-(Aminomethyl)benzyloxylstyrene]

α-[4-Methoxybenzyloxy)styrene]

α-Benzyloxy[4-(tert-butyldimethylsilyloxymethyl)styrene]

α-Benzyloxy[3-(tert-butyldimethylsilyloxymethyl)styrene]

α-Benzyloxy[4-(acetoxymethyl)styrene]

α-Benzyloxy[3-(acetoxymethyl)styrene]

α-Benzyloxy[4-(hydroxymethyl)styrene]

α-Benzyloxy[3-(hydroxymethyl)styrene]

α-Benzyloxy(4-chlorostyrene)

α-Benzyloxy(3-methoxystyrene)

α-Benzyloxy(4-methoxystyrene)

α-(4-Methoxycarbonylbenzyloxy)[4-(acetoxymethyl)styrene]

α-(4-Methoxycarbonylbenzyloxy)[3-(acetoxymethyl)styrene]

α-[4-(Hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene]

α-[4-(Hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene]

α-[4-(tert-Butyldimethylsilyloxymethyl)benzyloxy][4-(tert-butyldimethylsilyloxymethyl)styrene]

α-[4-(tert-Butyldimethylsilyloxymethyl)benzyloxy][3-(tert-butyldimethylsilyloxymethyl)styrene]

α-(4-Methoxycarbonylbenzyloxy)-4-cyanostyrene

α-[4-(Hydroxymethyl)benzyloxy][4-(aminomethyl)styrene]

α-Benzyloxyacrylonitrile

Methyl α-Benzyloxyacrylate

α-Benzyloxyacrylamide

The compounds of Formula II, described in the present invention, bearsuperficial resemblance to compounds of Formula III, which have beendisclosed previously as chain transfer agents in the Journal ofMacromolecular Science—Chemistry, 1984, A21, 979-995; in “Ring OpeningPolymerization: Kinetics, Mechanism, and Synthesis”, ACS SymposiumSeries No. 286, J. E. McGrath, Ed., Washington D.C.: 1985, chapter 4;and in “Reactive Oligomers”, ACS Symposium Series No. 282, F.W Harrisand H. J. Spinelli, Eds, Washington D.C., 1985, chapter 13.

In Formula III, R¹ and R² represent alkyl, benzyl, or substituted benzylgroups. The compounds of the present invention exhibit a much greaterresistance to hydrolytic decomposition, than do those of Formula III. Infact, processes involving compounds of the Formula III, unlike those ofthe present invention, have little practical utility for control ofmolecular weight on account of this hydrolytic lability, except,perhaps, under conditions where the monomers and any solvents used, aremost rigorously purified and maintained in a strictly anhydrouscondition.

Preparation of the Chain Transfer Agents Described in this Invention

α-(Alkanethiomethyl)styrenes

These compounds (Formula I, X=sulphur, R¹=phenyl, R²=substituted orunsubstituted alkyl, aryl, alkenyl, or alkynyl, n=1) can be readilyprepared via a nucleophilic substitution reaction involving thetreatment of a stirred alcoholic solution of α-(bromomethyl)styrene withthe appropriate thiol and a base, such as potassium carbonate orhydroxide, or sodium acetate, hydroxide or methoxide. It is usuallydesirable to use an equimolar ratio of the reagents. The startingmaterial α-(bromomethyl)styrene can be obtained using a proceduredescribed in The Journal of Organic Chemistry, 1957, 22, 1113, or in theJournal of the American Chemical Society, 1954, 76, 2705.

α-(t-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=t-butyl, n=1). [Typical procedure].t-Butanethiol (4 ml, 35.5 mmol) was added slowly at room temperature toa stirred suspension of potassium carbonate (5 g, 36 mmol) andα-(bromomethyl)styrene (7 g, 35.5 mmol) in absolute ethanol [ormethanol] (50 ml). Stirring was maintained for 16 h and then thereaction mixture was poured into water, and extracted (3×) with diethylether. The extracts were then dried over anhydrous Na₂SO₄, filtered, andevaporated to dryness. Distillation of the crude product through a shortcolumn afforded α-(t-butanethiomethyl)styrene (5 g, 69%) as a colourlessliquid: bp 88° C./3 mmHg. ¹H NMR (CDCl₃) δ 1.35 (9H, a, (CH ₃)₃C), 3.60(2H, 5, allylic CH ₂S), 5.30 (1H, 8, olefinic proton), 5.40 (1H, a,olefinic proton), 7.20-7.50 (5H, m, aromatic protons); ¹³C NMR (CDCl₃) δ30.8, (CH ₃)₃C; 33.4, allylic CH₂S; 42.7, SC(CH₃)₃; 115.0, H₂ C═C;126.2, 127.7, 128.3, 144.8, aromatic ring carbons; 140.0, H₂C═C; MS(CH₄)207 (MH⁺, 13%), 179 (26%), 151 (100%).

α-(n-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R² =n-butyl, n=1). This compound wasprepared using a similar procedure to that described above. Pureα-(n-butanethiomethyl)styrene was obtained in 90% yield after columnchromatography on silica-gel (petroleum spirit eluent): ¹H NMR (CDCl₃) δ0.85 (3H, t, CH₃CH₂, J 7.0 Hz), 1.20-1.70 (4H, m, CH₃ CH ₂ CH ₂CH₂S),2.45 (2H, t, CH₂ CH ₂S, J 7.0 Hz), 3.58 (2H, a, allylic CH₂S), 5.20 (1H,5, olefinic proton), 5.40 (1H, a, olefinic proton) 7.20-7.50 (5H, m,aromatic protons).

α-(Carboxymethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²—CH₂COOH, n=1). A solution ofα-(bromomethyl)styrene (7 g, 35.5 mmol) in methanol (15 ml) was added toa stirred solution at room temperature of sodium acetate (5.86 g, 71.4mmol) and thioglycolic acid (6.57 g, 71.4 mmol) in methanol (25 ml). Themixture was allowed to stir for 2 days and then was poured into amixture of water and saturated NaHCO₃ solution (1:1), and washed withdiethyl ether. The aqueous basic layer was adjusted to pH 1 withhydrochloric acid and then extracted three times with diethyl ether. Thecombined ether layers were then dried over anhydrous MgSO₄. Afterremoval of the solvent, the required compound (7.1 g, 95.5%) wasobtained, mp 74-76° C. (from CCl₄); ¹H NMR (CDCl₃) δ 3.20 (2H, S, SCH₂COOH), 3.70 (2H, 9, allylic CH₂S), 5.25 (1H, s, olefinic proton), 5.50(1H, 8, olefinic proton), 7.20-7.50 (5H, m, aromatic protons), 10.80(1H, broad singlet, COOH); MS (CH₄) 209 (MH⁺, 100%), 191 (50%), 163(91%), 117 (96%).

α-(Carboxyethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂CH₂COOH, n=1). Similarly,treatment of α-(bromomethyl)styrene with 3-mercaptopropionic acid andsodium acetate in methanol as described above, affordedα-(carboxyethanethiomethyl)styrene: mp 47-49° C. (from CCl₄); ¹H NMR(CDCl₃) δ 2.60-2.90 (4H, m, SCH ₂ CH ₂COOH), 3.60 (2H, s, allylic CH₂S),5.25 (1H, S, olefinic proton), 5.45 (1H, s, olefinic proton), 7.20-7.50(5H, m, aromatic protons), 8.35 (1H, broad singlet, COOH).

α-(2-Hydroxyethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂CH₂OH, n=1). The title compoundwas prepared in 90% yield after column chromatography on silica gel(ethyl acetate/petroleum spirit). ¹H NMR (CDCl₃) δ 2.35 (1H, broadsinglet, OH), 2.65 (2H, t, SCH ₂CH₂OH, J 7.0 Hz), 3.60 (2H, s, allylicCH₂S), 3.68 (2H, t, SCR₂ CH ₂COH, J 7.0 Hz), 5.30 (1H, s, olefinicproton), 5.45 (1H, s, olefinic proton), 7.20-7.50 (5H, m, aromaticprotons); ¹³C NMR (CDCl₃) δ 34.4, allylic CH₂S; 36.1, SCH ₂CH₂OH; 60.2,SCH₂ CH ₂OH; 115.3, H₂ CH═C; 126.3, 128.0, 128.4, 143.6, aromatic ringcarbons; 139.0, H₂C═C; MS (CH₄) 195 (MH⁺, 40%), 177 (100%), 149 (69%),135 (42%), and 119 (87%).

α-(2-Aminoethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂CH₂NR₂, n=1). A solution ofα-(bromomethyl)styrene (0.5 g, 2.55 mmol) in methanol (2 ml) was addedto a cold stirred solution of 2-aminoethanethiol (0.197 g, 2.55 mmol)and sodium methoxide (0.165 g, 3 mmol) in methanol (3 ml). After 15minutes at 0° C., the mixture was allowed to stir at room temperaturefor a further one hour. The resulting mixture was then poured into waterand acidified with dilute HCl, and then extracted with diethyl ether inorder to remove traces of the unreacted bromide. The acidic layer wasthen brought to pH 7-8 with KOH solution (5%) and then extractedimmediately with diethyl ether (3×). The combined ether extracts werethen dried (Na₂SO₄). After removal of the solvent, the product,α-(2-aminoethanethiomethyl)styrene, (0.42 g, 85%) was obtained as abrownish liquid: ¹H NMR (CDCl₃) δ 1.75 (2H, broad singlet, NH₂),2.45-2.85 (4H, A₂B₂ multiplets, SCH ₂ CH ₂NH₂), 3.55 (2H, m, allylicCH₂S), 5.15 (1H, m, olefinic proton), 5.40 (1H, m, olefinic proton),7.20-7.50 (5H, m, aromatic protons); MS (CH₄) 194 (MR⁺, 6%), 177 (100%),149 (54%).

α-[3-(Trimethoxysilyl)propanethiomethyl]styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂CH₂Si(OCH₃)₃, n=1). Thiscompound was prepared in 94% yield after rapid column chromatography onsilica gel (ethyl acetate). ¹H NMR (CDCl₃) δ 0.75 (2H, t, CH ₂Si, J 7.0Hz), 1.75 (2H, quintet, SCH₂ CH ₂CH₂Si), 2.55 (2H, t, SCH ₂CH₂CH₂Si, J7.0 Hz), 3.60 (2H, 8, allylic CH₂S), 3.60 (9H, s, 3×OCH ₃), 5.20 (1H, s,olefinic proton), 5.45 (1H, 8, olefinic proton), 7.20-7.50 (5H, m,aromatic protons).

α-(n-Butanesulphinylmethyl)styrene

(Formula 1, X=S(O), R¹=phenyl, R²=n-butyl, n=1). To a stirred solutionof α-(n-butanethiomethyl)styrene (1 g, 4.85 mmol) in CH₂Cl₂ (25 ml) at−78° C., a solution of m-chloroperbenzoic acid 90% (0.93 g, 5.40 mmol)in CH₂Cl₂ (25 ml) was added dropwise. The mixture was allowed to stir at−78° C. for 1 h before being poured into aqueous saturated NaHCO₃ (50ml). The organic layer was separated and the aqueous phase was extractedthree times with CH₂Cl₂. The combined organic phases were then washedwith water, dried over anhydrous Na₂SO₄, filtered, and the solvent wasremoved to give α-(n-butanesulphinylmethyl)styrene (1.05 g, 97%): mp42-43.5° C. (from petroleum spirit); ¹H NMR (CDCl₃) δ 0.90 (3H, t, CH₂CH ₃, J 7.0 Hz), 1.20-1.90 (4H, m, CH₂ CH ₂CH₂CH₃), 2.65 (2H, t, S(O) CH₂CH₂, J 7.0 Hz), 3.90 (2H, AB quartet, allylic CH ₂S(O), J_(AB) 15.0Hz), 5.35 (1H, a, olefinic proton), 5.55 (1H, 8, olefinic proton),7.20-7.50 (5H, m, aromatic protons); IR (film) 1040 cm⁻¹ (S—O); MS (CH₄)223 (Mb⁺, 100%), 117 (15%).

Alkyl α-(Alkanethiomethyl)acrylates

In principle, these compounds (Formula I, X=sulphur, R¹=—COOAlkyl,R²=substituted or unsubstituted alkyl, aryl, alkenyl, or alkynyl, n=1)could be prepared directly via reaction of an alkylα-(bromomethyl)acrylate, the appropriate thiol, and a base. However, analternative and generally more useful preparation, which is outlined inThe Journal of the Chemical Society, Perkin Transactions I, 1986,1613-1619, can be conveniently used to prepare the following compounds.

Ethyl α-(t-Butanethiomethyl)acrylate

(Formula I, X=sulphur, R¹=—COOCH₂CH₃, R²=t-butyl, n=1) has beenpreviously reported in the article cited above.

Ethyl α-(Carboxymethanethiomethyl)acrylate

(Formula I, X=sulphur, R¹=—COOCH₂CH₃, R²=—CH₂COOH, n=1). Thioglycolicacid (2.0 g, 22 mmol) was added slowly to a stirred suspension of ethyl1,3-dibromopropane-2-carboxylate (6.0 g, 21.9 mmol) and potassiumcarbonate (3.04 g, 22 mmol) in absolute ethanol (25 ml). After 2 h ofstirring at ambient temperature, the mixture was poured into saturatedaqueous NaHCO₃, and washed with diethyl ether. The aqueous layer wasacidified with dilute HCl and then extracted (5×) with diethyl ether.The combined ether extracts were then dried over anhydrous Na₂SO₄. Afterthe solvent was removed, vacuum distillation of the crude productafforded pure ethyl α-(carboxymethanethiomethyl)acrylate (1.3 g, 29%),as a slightly yellow liquid, bp 122-130° C. (0.05 mmHg), whichsolidified upon cooling in the freezer. 1H NMR (CDCl₃) δ 1.30 (3H, t,OCH₂ CH ₃, J 7.0 Hz), 3.20 (2H, a, SCH ₂COOH), 3.55 (2H, 5, allylicCH₂S), 4.25 (2H, q, OCH ₂CH₃, J 7.0 Hz), 5.65 (1H, 8, olefinic proton),6.25 (1H, a, olefinic proton), 10.55 (1H, broad a, exchangeable, COOH).

α-(Alkanethiomethyl)acrylic Acids

These compounds (Formula I, X=sulphur, R¹=COOH, R² =substituted orunsubstituted alkyl, aryl, alkenyl, or alkynyl, n=1) can be prepareddirectly from the corresponding esters [alkylα-(alkanethiomethyl)acrylates, prepared as described above] by treatmentwith aqueous KOH.

α-(Carboxymethanethiomethyl)acrylic Acid

(Formula I, X=sulphur, R¹=—COOH, R²=—CH₂COOH, n=1). This compound wasprepared from ethyl α-(carboxymethanethiomethyl)acrylate (0.5 g, 2.45mmol) and aqueous KOH (4% solution, 20 ml). The mixture was allowed tostir at room temperature overnight and then brought to pH 1 withhydrochloric acid. The resultant mixture was extracted with diethylether (5×). The combined extracts were then dried over anhydrous Na₂SO₄.After the solvent was removed, the product,α-(carboxymethanethiomethyl)acrylic acid (0.42 g, 97%), solidified. mp121-125° C.; 1H NMR (CD₃OD) δ 3.20 (2H, s, SCH ₂COOH), 3.50 (2H, s,allylic CH₂S), 4.90 (2H, broad singlet, 2×COOH), 5.70 (1H, a, olefinicproton), 6.20 (1H, s, olefinic proton). IR (KBr) 2500-3500 (broad),1680, 1700 cm⁻¹ (C═O). MS (CH₄) 177 (MH⁺, 5%), 159 (47%), 131 (100%).

α-(Alkanethiomethyl)acrylonitriles

In general, these compounds (Formula I, X=sulphur, R¹=—CN,R²=substituted or unsubstituted alkyl, aryl, alkenyl, or alkynyl, n=1)can be prepared by reaction of a cooled, stirred alcoholic solution ofα-(bromomethyl)acrylonitrile with the appropriate thiol and a base.

The starting material, α-(bromomethyl)acrylonitrile, was obtained usinga similar procedure to that described for the syntheses of ethylα-(hydroxymethyl)acrylate and ethyl α-(halomethyl)acrylates inSynthesis, 1982, 924-926. Thus, α-(hydroxymethyl)acrylonitrile (bp68-70° C. (0.3 mmHg)) was stirred with phosphorus tribromide in dryether at −10° C. to afford α-(bromomethyl)acrylonitrile, bp 45-47° C. (2mmHg); 1H NMR (CDCl₃) δ 3.85 (2H, broad singlet, allylic CH₂Br), 5.95(2H, m, olefinic protons).

α-(t-Butanethiomethyl)acrylonitrile

(Formula I, X=sulphur, R¹=—CN, R²=t-butyl, n=1).α-(Bromomethyl)acrylonitrile (1.18 g, 8 mmol) was converted to the titlecompound by treatment with a mixture of t-butanethiol (0.9 ml, 8 mmol),potassium carbonate (1.12 g, 8.1 mmol) and absolute ethanol (10 ml) at0° C. for 1 h. The resulting mixture was allowed to stand at roomtemperature for another hour before the usual workup. After columnchromatography on silica-gel (8% ethyl acetate/petroleum spirit),α-(t-butanethiomethyl)acrylonitrile (0.97 g, 77%) was obtained as acolourless liquid: ¹H NMR (CDCl₃) δ 1.35 (9K, s, (CH ₃)₃C), 3.35 (2H, m,allylic CH₂S), 5.95 (2H, m, olefinic protons); MS (CH₄) 156 (Mu⁺, 34%),128 (55%), 100 (100%).

α-(Diethoxyphosphorylmethyl)styrene

(Formula I, X=P(O), R¹=phenyl, R=—OCH₂CH₃, n=2). α-(Bromomethyl)styrenewas treated with an equimolar ratio of triethylphosphite at reflux for 1h. After the mixture was cooled to room temperature, the by-product,ethyl bromide, was removed under reduced pressure, and the productα-(diethoxyphosphorylmethyl)styrene was obtained in quantitative yieldas a yellowish syrup: ¹H NMR (CDCl₃) δ 1.20 (6H, t, 2×OCH₂ CH ₃, J 7.5Hz), 3.05 (2H, d, CH₂P(O), J 22.5 Hz), 4.00 (4H, m, 2×OCH ₂CH₃), 5.35(1H, d, olefinic proton, J 6.0 Hz), 5.50 (1K, d, olefinic proton, J 6Hz), 7.25-7.55 (5H, m, aromatic protons).

The following three chain transfer agents used in this invention wereprepared according to literature procedures.

Ethyl α-(Trimethylsilylaethyl)acrylate

(Formula I, X=Si, R¹=—COOCH₂CH₃, R²=—CH₃, n=3) as described inSynthesis, 1985, 271-272.

Ethyl α-(Benzenesulphonylmethyl)acrylate

(Formula I, X=S(O)₂, R¹=—COOCH₂CH₃, R²=phenyl, n=1) as described inJournal of the Chemical Society, Chemical Communications 1986 1339-1340.This compound was purified either by high vacuum distillation (bp136-140° C./0.05 mmHg) or by chromatography on silica-gel (ethylacetate:petroleum 2:3). ¹H NMR (CDCl₃) δ 1.20 (3H, t, OCH₂C₃, J 7.5 Hz),4.05 (2H, q, OCH₄CH₃, J 7.5 Hz), 4.20 (2H, s, allylic CH₂S(O)₂), 5.90(1H, s, olefinic proton) 6.50 (1H, s, olefinic proton), 7.40-8.00 (5H,m, aromatic protons).

Ethyl α-(Tri-n-butylstannylmethyl)acrylate

(Formula I, X=Sn, R¹=—COOCH₂CH₃, R²=n-butyl, n=3). This compound wasprepared from ethyl α-(benzenesulphonylmethyl)acrylate, n-Bu₃SnH andAIBN in benzene at 80° C. for 1.5 h according to the procedure describedin Journal of the Chemical Society, Chemical Communications, 1986,1339-1340. ¹H NMR (CDCl₃) δ 0.85-1.65 (30H, m, 3×CH ₂ CH ₂ CH ₂ CH ₂ CH₃, OCH₂CH₃), 2.00 (2H, s, allylic CH₂Sn), 4.15 (2H, q, OCH₂CH₃, J 7.5Hz), 5.25 (1H, s, olefinic proton), 5.75 (1H, s, olefinic proton).

α-Alkoxystyrenes (Formula II, R=phenyl)

One class of compound used in this invention, the α-alkoxystyrenes(Formula II; R¹=phenyl) can be cheaply and easily prepared from styrene,the appropriate alcohol, iodine and mercuric oxide, using a procedurebased on that described in Die Makromolekulare Chemie, 1967, 103, 68.This procedure is useful as a general synthesis and a number ofderivatives can be prepared, including those with substituents on thephenyl group of the styrene or on R². It is usually desirable to use anequimolar ratio of the reagents and to add a non-reactive solvent suchas petroleum ether or diethyl ether. When the compound II containscertain functional groups, the procedure is best modified to use analkoxide base, such as sodium methoxide (Method A) or potassiumtert-butoxide (Method B), or an amine base (Method C) in the eliminationstep. The compounds can be purified by chromatography on basic aluminaor, in some cases, by recrystallization or by distillation at reducedpressures. An alternative, but more costly method of synthesis is toreact the appropriate ester with a titanium-aluminium complex, asdescribed in The Journal of Organic Chemistry, 1985, 50, 1212.

General Procedure for the Preparation of an α-Alkoxystyrene by Method A:α-(4-Methoxicarbonylbenzyloxy)styrene

(Formula II, R¹=phenyl, R²=CH₃OC(O)C₆H₄CH₂—). Iodine (6.35 g, 25 mmol)was added in small portions to a stirred suspension, maintained between0 and 10° C., of yellow mercuric oxide (5.34g, 25 mmol), styrene (2.6 g,25 mmol), and methyl 4-(hydroxymethyl)benzoate (4.15 g, 25 mmol) inether (5 ml). The resulting mixture was stirred for 1 h at 0° C. andthen warmed to ambient temperature and stirred for a further 1 h. Themixture was then diluted with ether, and filtered. The filtrate waswashed successively with water, aqueous sodium thiosulphate solution anda further two portions of water, and then dried (MgSO₄). The solvent wasremoved to afford the intermediate iodoether which was converted to thealkoxystyrene by addition to a boiling solution of sodium methoxide inmethanol [prepared from sodium (1.15 g, 50 mmol) and methanol (25 ml)].After the resulting mixture had been heated for 1 h under reflux, it wascooled, diluted with water and extracted with ether. The organic layerwas washed with water and dried (K₂CO₃). After removal of the solvent,the crude mixture was chromatographed on basic alumina (30%CH₂Cl₂/petroleum spirit) to afford α-(4-methoxycarbonylbenzyloxy)styrene(1.3 g, 20%): ¹H NMR (CDCl₃) δ 3.85 (3H, s), 4.24 (1H, d, J 3 Hz),. 4.72(1H, d, J 3 Hz), 4.97 (2H, a), 7.2-7.7 (7H, m), 8.03 (2H, d, J 8 Hz); MS(CH₄) 269 (MH⁺, 15%), 149 (100%); IR (film) 1735 cm¹.

General Procedure for the Preparation of an α-Alkoxystyrene by Method B:α-Benzyloxy[4-(chloromethyl)styrene] andα-Benzyloxy[3-(chloromethyl)styrene]

(Formula II, R¹=ClCH₂C₆H₄—, R²=benzyl). Treatment of a 2:3 mixture (7.63g, 50 mmol) of 4-(chloromethyl)styrene and 3-(chloromethyl)styrene withbenzyl alcohol (5.4 g, 50 mmol), iodine (12.7g, 50 mmol), and mercuricoxide (10.8 g, 50 mmol), as described above, afforded the intermediateiodoether (18 g). Potassium tert-butoxide (0.28 g, 2.5 mmol) was addedto a solution of the iodoether (0.48 g, 1.2 mmol) in ether (10 ml) andthe mixture was allowed to stir at room temperature for 2 h. The mixturewas then poured into saturated sodium chloride solution and water (1:1)and extracted three times with 50% ether/petroleum spirit. The combinedextracts were washed with water and dried (K₂CO₃) to afford, afterchromatography as described above, the required alkoxystyrene (260 mg):1H NMR 6 4.33 (1H, d, J 1.9 Hz), 4.53 (2H, 8), 4.73 (1H, d, J 1.9 Hz),4.93 (2H, s), 7.1-7.7 (9H, m); MS (CH₄) 259, 261 (3:1, MH⁺, 1%), 91(100%).

General Procedure for the Preparation of an α-Alkoxystyrene by Method C:α-(4-Cyanobenzyloxy)styrene

(Formula II, R¹=phenyl, R²=4-NCC₆H₄CH₂—). Treatment of 4-cyanobenzylalcohol (5.98 g, 45 mmol) [prepared by sodium borohydride reduction (2h, 20° C., EtOH) of 4-cyanobenzaldehyde] with styrene, iodine, andmercuric oxide, as described above, afforded the intermediate iodoether(9 g, 55%). 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN) (3,5 g, 28 mmol) Wasadded to a stirred suspension of the iodoether (8.5 g, 23 mmol),powdered potassium carbonate (2.12 g, 35 mmol), and acetonitrile (12ml). After the resultant mixture was stirred at ambient temperatureovernight, it was diluted with water and extracted twice with ether. Thecombined ether extracts were washed with water and aqueous sodiumbicarbonate solution, dried (K₂CO₃), and purified by chromatography onalumina to afford the required compound (3.5 g, 65%), which was furtherpurified by recrystallization (CH₂Cl₂/petroleum spirit): mp 54-55° C.;¹H NMR C 4.20 (1H, d, J 3 Hz), 4.67 (1H, d, J 3 Hz), 4.95 (2H, s),7.1-7.7 (9H, m).

The following compounds were also prepared.

α-[4-(Hydroxymethyl)benzyloxy]styrene

(Formula II, R¹=phenyl, R²=4-HOCH₂C₆H₄CH₂—). This compound was preparedby lithium aluminium hydride reduction ofα-(4-methoxycarbonylbenzyloxy)styrene: ¹H NMR (CCl₄) δ 2.65 (1H, t, J4.5 Hz), 4.15 (11, d, J 3 Hz), 4.43 (2H, d, J 4.5 Hz), 4.60 (1H, d, J 3Hz), 4.80 (2H, 8), 7.1-7.7 (9H, m). α-[4-(Aminomethyl)benzyloxylstyrene

(Formula II, R¹=phenyl, R²=4-H₂NCH₂C₆H₄CH₂—). Lithium aluminium hydridereduction of α-(4-cyanobenzyloxy)styrene led to this compound: ¹H NMR(CD₃OD) δ 3.73 (2H, br 8), 4.30 (1H, d, J 3 Hz), 4.70 (1H, d, J 3 Hz),4.72 (2H, 9), 4.87 (2H, 9), 7.1-7.7 (9H, m).

α-(⁴-Methoxybenzyloxy)styrene

(Formula II, R¹=phenyl, R²=4-CH₃OC₆H₄CH₂—). Prepared using Method A. ¹HNMR (CDCl₃) δ 3.73 (3H, s), 4.28 (1H, d, J 3 Hz), 4.70 (1H, d, J 3 Hz),4.83 (2H, s), 6.7-7.7 (9H, m); MS (CH₄) 241 (MH⁺, 8%), 121 (100%).

α-Benzyloxy[4-(tert-butyldimethylsilyloxymethyl)styrene] andα-Benzyloxy[3-(tert-butyldimethylsilyloxymethyl)styrene]

(Formula II, R¹=(tert-butyldimethylsilyloxymethyl)phenyl, R²=benzyl).(Hydroxymethyl)styrene was prepared from (chloromethyl)styrene (a 2:3mixture of para and meta isomers) by a sequence described in Polymer,1973, 14, 330. It was treated with tert-butyldimethylsilyl chloridefollowing the general directions found in Journal of the AmericanChemical Society, 1972, 94, 6190. Method C was used to convert theresulting compound to the required alkoxystyrene: ¹H NMR (CCl₄) δ 0.70(6H, s), 0.94 (9H, s), 4.17 (1H, d, J 2.4 Hz), 4.63 (3H, broadened s),4.83 (2H, s), 7.0-7.6 (9H, m); MS (CH₄) 355 (MH⁺, 4%), 91 (100%).

α-Benzyloxy[4-(acetoxymethyl)styrene] andα-Benzyloxy[3-(acetoxymethyl)styrene]

(Formula II, R¹=CH₃COOCH₂C₆H₄—, R²=benzyl). (Acetoxymethyl)styrene wasprepared from (chloromethyl)styrene by the method described in Polymer,1973, 14, 330. It was converted (Method C) to the requiredalkoxystyrene: ¹H NMR (CCl₄) δ 2.02 (3H, 8), 4.23 (1H, d, J 2 Hz), 4.67(1H, d, J 2 Hz), 4.87 (2H, s), 5.00 (2H, s), 7.0-7.7 (9H, m);MS (CH₄)283 (MH⁺, 1%), 91 (100%); IR 1740 cm⁻¹

α-Benzyloxy[4-(hydroxymethyl)styrene] andα-Benzyloxy[3-(hydroxymethyl)styrene]

(Formula II, R¹=HOCH₂C₆H₄—, R²=benzyl). These compounds were obtained bylithium aluminium hydride reduction ofα-benzyloxy[(acetoxymethyl)styrene]. ¹H NMR (CCl₄) δ 2.96 (1H, t, J 4.5Hz), 4.20 (1H, d, J 2.5 Hz), 4.40 (2H, d, J 4.5 Hz), 4.63 (1H, d, J 2.5Hz), 4.85 (2H, s), 7.0-7.8 (9H, m); IR 3320 (broad) cm⁻¹.

α-Benzyloxy(4-chlorostyrene)

(Formula II, R¹=4-ClC₆H₄—R²=benzyl). Prepared using Method A. ¹H NMR(CDCl₃) δ 4.20 (1H, d, J 3 Hz), 4.63 (1H, d, J 3 Hz), 4.80 (2H, s),7.0-7.6 (9H, m); MS (CH₄) 245, 247 (3:1, MH⁺, 1%), 91 (100%).

α-Benzyloxy(3-methoxystyrene)

(Formula 1I, R¹=3-CH₃OC₆H₄—, R²=benzyl). Prepared using Method A. ¹H NMR(CDCl₃) δ 3.74 (3H, s), 4.30 (1H, d, J 3 Hz), 4.71 (1H, d, J 3 Hz), 4.92(2H, s), 6.7-6.9 (1H, m), 7.1-7.5 (8H, m); MS (CH₄) 241 (MH₊, 11%), 91(100%).

α-Benzyloxy(4-methoxystyrene).

(Formula II, R¹=4-CH₃OC₆H₄—, R²=benzyl). Prepared using Method A. ¹H NMR(CDCl₃) δ 3.70 (3H, s), 4.03 (1H, d, J 3 Hz), 4.60 (1H, d, J 3 Hz), 4.90(2H, s), 6.6-7.6 (9H, m).

α-(4-Methoxycarbonylbenzyloxy)[4-(acetoxymethyl)styrene] andα-(4-Methoxycarbonylbenzyloxy) [3-(acetoxymethyl)styrene].

Formula II, R¹=CH₃COOCH₂C₆H₄—, R²=4-CH₃OC(O)C₆H₄CH₂—). Prepared usingMethod C. ¹H NMR (CCl₄) δ 1.98 (3H, 9), 3.80 (3H, s), 4.20 (1H, d, J 3Hz), 4.68 (1H, d, J 3 Hz), 4.8-5.0 (4H, m), 7.1-8.0 (8R, m).

α-[4-(Hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] andα-[4-(Hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene]

(Formula II, R¹=HOH₂C₆H₄—, R²=HOCH₂C₆H₄C₂) Lithium aluminium hydridereduction of α-(4-methoxycarbonylbenzyloxy)[4-(acetoxymethyl )styrene]and α-(4-methoxycarbonylbenzyloxy) [3-(acetoxymethyl)styrene] gave therequired compounds: ¹H NMR (CD OD) δ 4.33 (1H, d, J 2 Hz), 4.58 (4H, s),4.77 (3H, broadened s), 4.92 (2R, s), 7.1-7.7 (8H, m.

α-[4-(tert-Butyldimethylsilyloxymethyl)benzyloxy][4-(tert-butyldimethylsilyloxymethyl)styrene]andα-[(tert-butyldimethylsilyloxymethyl)benzyloxy][3-(tert-butyldimethylsilyloxymethyl)styrene].(Formula II, R¹=tert-butyldimethylsilyloxymethylphenyl,R²=4-tert-butyldimethylsilyloxymethylbenzyl). Methyl4-(hydroxymethyl)benzoate was treated with tert-butyldimethylsilylchloride using the general procedure described in Journal of theAmerican Chemical Society, 1972, 94, 6190. The resulting product wasreduced with lithium aluminium hydride to afford4-(tert-butyldimethylsilyloxymethyl)benzyl alcohol. This alcohol wasconverted into the required compound using Method C. ¹H NMR (CCl₄) δ0.08 (32H, s), 0391 (18H, s), 4.22 (1H, d, J 2 Hz), 4.68 (5H, br s),4.90 (2H, a), 7.1-7.6 (8H, m); MS (CH₄) 483 (M⁺−CH₃, 52%), 133 100%).

α-(4-Methoxycarbonylbenzyloxy)-4-cyanostyrene

(Formula II, R¹=4-NCC₆H₄—, R²=4-CH₃OC(O)C₆H₄CH₂—). Prepared using MethodC, ¹ H NMR (CCl₄) δ 3.85 (3H, s), 4.23 (1H, d, J 3 Hz), 4.65 (1H, d, J 3Hz), 4.97 (2H, s), 7.0-8.1 (8H, m).

α-[⁴-(Hydroxymethyl)benzyloxy][⁴-(aminomethyl)styrene]

(Formula II, R¹=4-H₂NCH₂C₆H₄—, R²=4-HOCH₂C₆H₄CH₂—). Lithium aluminiumhydride reduction of α-(4-methoxycarbonylbenzyloxy)-4-cyanostyrene gavethe required compound. ¹H NMR (CD₃OD) δ4.35 (1H, d, J 3 Hz), 4.58 (2H,s), 4.77 (6H, broadened s), 4.93 (2H, a), 7.0-7.7 (8H, m).

α-Alkoxyacrylonitriles

These compounds (Formula II, R¹=—CN) were prepared by a short sequencedescribed in The Journal of the Chemical Society, 1942, 520, using theappropriate alcohol. The elimination step was best accomplished bystirring of the intermediate halocompound at ambient temperatures inacetonitrile containing 2 molar equivalents of DBN(1,5-diazabicyclo[4.3.0]non-5-ene) and 1.1 molar equivalents ofpotassium carbonate (similar to Method B, above).

α-Benzyloxyacrylonitrile

(Formula II, R¹=—CN, R²=benzyl). This compound, which had not previouslybeen reported, was obtained using the above procedure. bp 55-58° C.(0.025 mmHg); ¹H NMR (CDCl₃) δ 4.83 (2H, s), 4.93 and 5.00 (2H, ABq,J_(AB) 3 Hz), 7.33 (5H, s); MS (CH₄) m/e 160 (MH⁺, 71%), 91 (100%); IR2235 cm⁻¹.

α-Alkoxyacrylates

These compounds (Formula II; R¹ =—COOAlkyl) can be prepared from estersof 2,3-dibromopropionic acid by treatment with alkoxides, following theprocedure described in Bulletin of the Chemical Society of Japan, 1970,43, 2987. An alternative and generally more useful preparation is from aprecursor to the corresponding nitrile (Formula II; R¹=—CN) by treatmentwith gaseous hydrogen chloride and a solution containing the appropriatealcohol, based on the procedure outlined in Bulletin of the ChemicalSociety of Japan, 1969, 42, 3207.

Methyl α-Benzyloxyacrylate

(Formula II, R¹=CH₃OC(O)—, R²=benzyl). A slow stream of hydrogenchloride gas was passed for 4 h through a solution of2-benzyloxy-3-bromopropionitrile (16.75 g) in methanol (2.38 g) andether (66 ml) which was maintained at −10° C. The mixture was allowed tostand at 5° C. overnight, and then ice was added in small portions tothe mixture at 0° C. After 20 min of stirring, the mixture was pouredinto water and the product was extracted with ether, washed with waterand aqueous sodium bicarbonate, and dried (MgSO₄). After the solvent wasremoved, the crude product was recrystallized from ether/CH₂Cl₂ toafford, after a first crop of crystals of2-benzyloxy-3-bromopropanamide, the required intermediate, methyl2-benzyloxy-3-bromopropanoate. This bromoester was treated withDBN/potassium carbonate as described above to yield methylα-benzyloxyacrylate, mp 44.5-45.5° C. (from hexane); ¹H NMR δ 3.80 (3H,s), 4.63 (1H, d, J 3 Hz), 4.83 (2H, s), 5.37 (1H, d, J 3Hz), 7.33 (5H,s); IR 1740 cm⁻¹. Ketals of alkyl pyruvates, prepared-according to thedirections in The Journal of Organic Chemistry, 1967, 32,1615, also maybe converted to α-alkoxyacrylates by an acidic catalyst, as described inChemische Berichte, 1911, 44, 3514.

α-Alkoxyacrylamides

α-Benzyloxyacrylamide

(Formula II, R¹='CONH₂, R²=benzyl). Treatment of2-benzyloxy-3-bromopropanamide with DBN/potassium carbonate followingthe general procedure of Method C (above) yielded α-benzyloxyacrylamide(Formula II; R¹=—CONH2), mp 132-133° C.; ¹H NMR (CDCl₃) δ 4.53 (1H, d, J3 Hz), 4.80 (2H, s), 5.43 (1H, d, J 3 Hz), 6.50 (2H, br s), 7.33 (5H,s).

The following examples illustrate the use of the invention to producepolymers of controlled molecular weight and end-group functionality.

EXAMPLES OF THE PROCESS Example 1

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using α-(t-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=t-butyl, n=1).

Azobisisobutyronitrile (AIBN) (49.5 mg) was dissolved in freshlydistilled methyl methacrylate (25 ml). An aliquot (4 ml) was removed andadded to an ampoule containing the amount ofα-(t-butanethiomethyl)styrene (Ia) shown in Table I. The mixture waspolymerized at 60° C. for 1 h in the absence of oxygen. The contents ofthe ampoule were then poured into petroleum spirit (bp 40-60° C.) andthe precipitated polymer was collected and dried in a vacuum oven at 40°C. to constant weight. A small portion was examined by GPC using aWaters Instrument connected to six P-Styragel columns (10⁶-, 10⁵-, 10⁴-,10³-, 500- and 100-Å pore size). Tetrahydrofuran was used as eluent at aflow rate of 1 ml/min and the system was calibrated using narrowdistribution polystyrene standards (Waters).

TABLE I Amount of Ia added (mg) % conversion {haeck over (M)}_(n)* 010.9 205,190 9.0 10.4 46,071 17.4 10.1 27,870 31.4 9.4 16,795 61.6 8.69,600 *Polystyrene-equivalent number average molecular weight, obtainedby GPC

The chain transfer constant calculated from these data was 1.24, whichcompares favourably with, say, n-butanethiol (chain transferconstant=0.66) or t-butanethiol (chain transfer constant=0.18). Theseresults show that the compound is an efficient chain transfer agent andthat the process produces polymers of low molecular weight in acontrolled manner. A sample of poly(methyl methacrylate) producedsimilarly using 298 mg of the chain transfer agent was precipitated twofurther times from ethyl acetate/petroleum spirit to remove traces ofthe unreacted chain transfer agent. The resulting polymer ofnumber-average molecular weight 3230 had signals at δ 4.95, and 5.15 ppmin the ¹H NMR spectrum confirming the presence of the terminal doublebond. Integration of the spectrum showed that one of these groups waspresent per polymer chain. The ¹³C NMR spectrum also confirmed thepresence of this group.

Example 2

Preparation of Low Molecular Weight Olefin-Terminated Polymers ofStyrene Using α-(t-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=t-butyl, n=1).

Azobisisobutyronitrile (34.3 mg) was dissolved in freshly distilledstyrene (25 ml). Aliquots (5 ml) were removed and added to ampoulescontaining the amount of α-(t-butanethiomethyl)styrene shown below. Themixtures were polymerized at 60° C. for 3 h in the absence of oxygen.The contents of the ampoules were then poured into methanol and theprecipitated polymer was collected and dried and examined by GPC asdescribed above. Samples of polystyrene prepared in this manner using 0mg, 10.58 mg, 20.12 mg, and 30.73 mg of the chain transfer agent hadnumber-average molecular weights of 125000, 61167, 46466, and 28964,respectively. The chain transfer constant calculated from these data was0.8, which compares favourably with that of n-butanethiol (chaintransfer constant=22) or dodecanethiol (chain transfer constant=15-19).These results show that o-(t-butanethiomethyl)styrene is an efficientchain transfer agent for styrene and that the process produces polymersof low molecular weight in a controlled manner. A sample of polystyreneproduced similarly using 320 mg of the chain transfer agent wasprecipitated two further times from ethyl acetate/methanol to removetraces of the unreacted chain transfer agent. The resulting polymer ofnumber-average molecular weight 3613 had signals at δ 4.7-4.8 and5.0-5.1 in the ¹H NMR spectrum confirming the presence of a terminaldouble bond. Integration of the spectrum showed that one of these groupswas present per polymer chain.

Example 3

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylAcrylate Using α-(t-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=t-butyl, n=1).

Azobisisobutyronitrile (9.88 mg) was dissolved in freshly distilledmethyl acrylate (25 ml). An aliquot (4 ml) was removed and added to anampoule containing thiophene-free benzene (16 ml) and the amount ofα-(t-butanethiomethyl)styrene shown below. The mixture was polymerizedat 60° C. for 1 h in the absence of oxygen. The volatiles were thenremoved and the polymers were dried in vacuo to constant weight andexamined by GPC. Samples of poly(methyl acrylate) prepared in thismanner using 0 mg, 7.78 mg, 11.67 mg, and 15.55 mg ofα-(t-butanethiomethyl)styrene had number-average molecular weights of496642, 24044, 15963, and 12211, respectively. The chain transferconstant calculated from these data was 3.95. These results show thatα-(t-butanethiomethyl)styrene is an efficient chain transfer agent formethyl acrylate and that the process produces polymers of low molecularweight in a controlled manner.

Example 4

Preparation of Low Molecular Weight Olefin-Terminated Polymers of VinylAcetate Using α-(t-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=t-butyl, n=1).

Azobisisobutyronitrile (8.0 mg) was dissolved in freshly distilled vinylacetate (50 ml). Aliquots (10 ml) were removed and added to ampoulescontaining the amounts of α-(t-butanethiomethyl)styrene shown below. Themixtures were then polymerized at 60° C. for 1 h in the absence ofoxygen. The volatiles were then removed and the polymers were dried invacuo to constant weight. The polymers were then examined by GPC asdescribed above. Samples of poly(vinyl acetate) prepared in this mannerusing 0 mg, 6.3 mg, 12.4 mg, and 24.2 mg ofα-(t-butanethiomethyl)styrene had number-average molecular weights of271680, 13869, 7286, and 3976, respectively. The chain transfer constantcalculated from these data was 19.9, which is closer to the ideal thanthat of n-butanethiol (chain transfer constant=48). These results showthat α-(t-butanethiomethyl)styrene is an efficient chain transfer agentfor vinyl acetate and that the process produces polymers of lowmolecular weight in a controlled manner.

Example 5

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using α-(n-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=n-butyl, n=1).

Azobisisobutyronitrile (49.5 mg) was dissolved in freshly distilledmethyl mathaerylate (25 ml). An aliquot (5 ml) was removed and added toan ampoule containing the amount of α-(n-butanethiomethyl)styrene shownbelow. The mixture was polymerized at 60° C. for 1 h in the absence ofoxygen. The volatiles were then removed and the polymers were dried invacuo to constant weight. A small portion was examined by GPC asdescribed above. Samples of poly(methyl methacrylate) prepared using 0mg and 20.4 mg of α-(n-butanethiomethyl)styrene had number-averagemolecular weights of 280190 and 37405, respectively. The chain transfer-constant calculated from these data is 1.10. These results show thatα-(n-butanethiomethyl)styrene is an efficient chain transfer agent formethyl methacrylate and that the process produces polymers of lowmolecular weight.

Example 6

Preparation of Low Molecular Weight Olefin-Terminated Polymers ofStyrene Using α-(n-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=n-butyl, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,19.7 mg, and 39.2 mg of α-(n-butanethiomethyl)styrene had number-averagemolecular weights of 118140, 45909, and 26922, respectively. The chaintransfer constant calculated from these data was 0.68. These resultsshow that M-(n-butanethiomethyl)styrene acts as an efficient chaintransfer agent for styrene and that the process produces polymers of lowmolecular weight.

Example 7

Preparation of Low Molecular Weight α-Carboxy, ω-Unsaturated Polymers ofMethyl Methacrylate Using α-(Carboxymethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂COOH, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 10.0 mg, 20.0 mg, and 40.0 mg ofα-(carboxymethanethiomethyl)styrene had number-average molecular weightsof 224730, 60531, 31869, and 17728, respectively. The chain transferconstant calculated from these data was 1.30. These results show thatα-(carboxymethanethiomethyl)styrene is an efficient chain transfer agentfor methyl methacrylate and that the process produces polymers of lowmolecular weight terminated by a carboxylic acid group. A sample ofpoly(methyl methacrylate) produced similarly using 300 mg of the chaintransfer agent (reaction time 4 h) was precipitated two further timesfrom ethyl acetate/petroleum spirit to remove traces of the unreactedchain transfer agent. The resulting polymer of number-average molecularweight 3291 had signals at δ 4.95 and 5.15 in the ¹H NMR spectrumconfirming the presence of a terminal double bond. Integration of thespectrum showed that there was on average one of these double bondspresent per polymer chain.

Example 8

Preparation of Low Molecular Weight α-Carboxy, ω-Unsaturated PolystyreneUsing α-(Carboxymethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂COOH, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,10.0 mg, 20.0 mg, and 30.3 mg of α-(carboxymethanethiomethyl)styrene hadnumber-average molecular weights of 125000, 54700, 33800, and 26300,respectively. The chain transfer constant calculated from these data was1.00. These results show that α-(carboxymethanethiomethyl)styrene is anefficient chain transfer agent for styrene and that the process producespolymers terminated by a carboxylic acid group of low molecular weight.A sample of polystyrene produced similarly using 500 mg of the chaintransfer agent was precipitated two further-times from ethylacetate/methanol to remove traces of the unreacted chain transfer agent.The resulting polymer of number-average molecular weight 2600 hadsignals at δ 4.7-4.8 and at δ 5.0-5.1 in the ¹H NMR spectrum confirmingthe presence of a terminal double bond. Integration of the spectrumshowed that one of these groups was present per polymer chain. Theinfrared spectrum of the polymer showed absorptions at 2500-3000, 1710,and 1300 cm⁻¹ confirming the presence of a carboxylic acid group.

Example 9

Preparation of Low Molecular Weight α-Carboxy, ω-Unsaturated Polymers ofStyrene Using α-(Carboxyethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂CH₂COOH, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,10.3 mg, 20.2 mg, and 40.3 mg of α-(carboxyethanethiomethyl)styrene hadnumber-average molecular weights of 114340, 56829, 47871, and 30014,respectively. The chain transfer constant calculated from these data was0.70. These results show that α-(carboxyethanethiomethyl)styrene is anefficient chain transfer agent for styrene and that the process producespolymers terminated by a carboxylic acid group of low molecular weight.

EXAMPLE 10

Preparation of Low Molecular Weight α-Hydroxy, ω-Unsaturated Poly(methylmethacrylate) Using α-(2-Hydroxyethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=CH₂CH₂OH, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 9.9 mg, 20.1 mg, and 40.0 mg ofα-(2-hydroxyethanethiomethyl)styrene had number-average molecularweights of 274490, 56921, 34200, and 17808, respectively. The chaintransfer constant calculated from these data was 1.20. These resultsshow that α-(2-hydroxyethanethiomethyl)styrene is an efficient chaintransfer agent for methyl methacrylate and that the process producespolymers of low molecular weight terminated by an alcohol group.

Example 11

Preparation of Low Molecular Weight α-Hydroxy, ω-Unsaturated Polymers ofStyrene Using α-(2-Hydroxyethanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂CH₂OH ,n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,9.9 mg, 20.1 mg, and 29.9 mg of α-(2-hydroxyethanethiomethyl)styrene hadnumber-average molecular weights of 116570, 57890, 38415, and 28855,respectively. The chain transfer constant calculated from these data was0.77. These results show that α-(2-hydroxyethanethiomethyl)styrene is anefficient chain transfer agent for styrene and that the process producespolymers of low molecular weight terminated by an alcohol group. Asample of polystyrene produced similarly using 201 mg of the chaintransfer agelit was precipitated two further times from ethylacetate/methanol to remove traces of the unreacted chain transfer agent.The resulting polymer of number-average molecular weight 6346 hadsignals at δ 3.35-3.55, 4.7-4.8, and 5.0-5.1 in the ¹H NMR spectrumconfirming the presence of a hydroxymethylene group and a terminaldouble bond. Integration of the spectrum showed that one each of thesegroups was present per polymer chain.

Example 12

Preparation of Low Molecular Weight α-Amino, ω-Unsaturated Polymers ofMethyl Methacrylate Using

α-(2-Aminoethanethiomethyl)styrene (Formula I, X=sulphur, R¹=phenyl,R²=—CH₂CH₂NH₂, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 11.9 mg, 21.2 mg, and 41.3 mg oft-(2-aminoethanethiomethyl)styrene had number-average molecular weightsof 185519, 49427, 32334, and 19065, respectively. The chain transferconstant calculated from these data was 1.05. These results show thatα-(2-aminoethanethiomethyl)styrene is an efficient chain transfer agentfor methyl methacrylate and that the process produces polymers of lowmolecular weight terminated by an amine group.

Example 13

Preparation of Low Molecular Weight α-Amino, ω-Unsaturated Polymers ofStyrene Using α-(2-Aminoethanethiomethyl)styrene (Formula I, X=sulphur,R¹=phenyl, R₂=—CH₂CH₂NH₂, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,10.4 mg, 20.2 mg, and 42.3 mg of α-(2-aminoethanethiomethyl)styrene hadnumber-average molecular weights of 134116, 60766, 39861, and 21920,respectively. The chain transfer constant calculated from these data was0.79. These results show that α-(2-aminoethanethiomethyl)styrene is anefficient chain transfer agent for styrene and that the process producespolymers of low molecular weight terminated by an amino group. A sampleof polystyrene produced similarly using 294 mg of the chain transferagent was precipitated two further times from toluene/methanol to removetraces of the unreacted chain transfer agent. The resulting polymer ofnumber-average molecular weight 8376 had signals at δ 3.1-3.2, 4.7-4.8,and at 5.0-5.1 in the ¹H NMR spectrum confirming the presence of theaminomethylene group and a terminal double bond. Integration of thespectrum showed that one of these groups was present per polymer chain.

Example 14

Preparation of Low Molecular Weight α-Trimethoxysilyl, ω-UnsaturatedPolymers of Styrene Usingα-(3-(Trimethoxysilyl)propanethiomethyl]styrene

(Formula I, X=sulphur, R¹=phenyl, R²=—CH₂CH₂CH₂Si(OCH₃)₃, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,and 400.7 mg of α-[3-(trimethoxysilyl)propanethiomethyl]styrene hadnumber-average molecular weights of 92287 and 8201, respectively. Thechain transfer constant calculated from these data was 0.40. Theseresults show that α-[3-(trimethoxysilyl)propanethiomethyl]styrene is anefficient chain transfer agent for styrene and that the process producespolymers terminated by a trimethoxysilyl group of low molecular weight.

Example 15

Preparation of Low Molecular Weight α-Bromo, ω-Unsaturated Polymers ofMethyl Methacrylate Using α-(Bromomethyl)styrene

(Formula I, X=Br, R¹=phenyl, n=0).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 24.96 mg, and 49.30 mg of α-(bromomethyl)styrene hadnumber-average molecular weights of 220453, 16118, and 7863,respectively. The chain transfer constant calculated from these data was2.27. These results show that α-(bromomethyl)styrene is an efficientchain transfer agent for methyl methacrylate and that the processproduces polymers terminated by a bromine end-group of low molecularweight. The sample of poly(methyl methacrylate) with number-averagemolecular weight 7863 was precipitated two further times from ethylacetate/petroleum spirit to remove traces of the unreacted chaintransfer agent. The resulting polymer had signals at δ 3.60, 5.00, and5.20 in the ¹H NMR spectrum confirming the presence of a BrCH₂ group anda terminal double bond.

Example 16

Preparation of Low Molecular Weight α-Bromo, ω-Unsaturated Polymers ofStyrene Using α-(Bromomethyl)styrene

(Formula I, X=Br, R¹=phenyl, n=0).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,15.76 mg, and 27.5 mg of α-(bromomethyl)styrene had number-averagemolecular weights of 130189, 17024, and 10157, respectively. The chaintransfer constant calculated from these data was 2.93. These resultsshow that α-(bromomethyl)styrene is an efficient chain transfer agentfor styrene and that the process produces polymers terminated by abromine end-group of low molecular weight.

Example 17

Preparation of Low Molecular Weight α-Bromo, ω-Unsaturated Polymers ofMethyl Acrylate Using α-(Bromomethyl)styrene

(Formula I, X=Br, R¹=phenyl, n=0).

Samples of poly(methyl acrylate) prepared in the manner of example 3using 0 mg, 10.57 mg, 15.86 mg, and 21.15 mg of α-(bromomethyl)styrenehad number-average molecular weights of 245048, 12675, 7922, and 6549,respectively. The chain transfer constant calculated from these data was5.25. These results show that C-(bromomethyl)styrene is an efficientchain transfer agent for methyl acrylate and that the process producespolymers of low molecular weight terminated by a bromine end-group.

Example 18

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using Ethyl -α-(t-Butanethiomethyl)acrylate (Formula I,X=sulphur, R¹=—COOCR₂CH₃, R²=t-butyl, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 12.2 mg, 22.6 mg, and 43.1 mg of ethylα-(t-butanethiomethyl)acrylate had number-average molecular weights of136696, 61799, 40776, and 24539, respectively. The chain transferconstant calculated from these data was 0.74. These results show thatethyl α-(t-butanethiomethyl)acrylate is an efficient chain transferagent for methyl methacrylate and that the process produces polymers oflow molecular weight in a controlled manner.

Example 19

Preparation of Low Molecular Weight Olefin-Terminated Polymers ofStyrene Using Ethyl α-(t-Butanethiomethyl)acrylate (Formula I,X=sulphur, R¹=—COOCH₂CH₃, R²=t-butyl, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,10.3 mg, 21.7 mg, and 40.0 mg of ethyl α-(t-butanethiomethyl)acrylatehad number-average molecular weights of 103583, 47806, 30606, and 19359,respectively. The chain transfer constant calculated from these data was0.95. These results show that ethyl α-(t-butanethiomethyl)acrylate is anefficient chain transfer agent for styrene and that the process producespolymers of low molecular weight in a controlled manner.

Example 20

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylAcrylate Using Ethyl α-(t-Butanethiomethyl)acrylate

(Formula I, X=sulphur, R¹=—COOCH₂CH₃, R²=t-butyl, n=1).

Samples of poly(methyl acrylate) prepared in the manner of example 3using 0 mg, 5.7 mg, 8.6 mg, and 11.4 mg of ethylα-(t-butanethiomethyl)acrylate had number-average molecular weights of842397, 50611, 38942, and 29012, respectively. The chain transferconstant calculated from these data was 2.23. These results show thatethyl α-(t-butanethiomethyl)acrylate is an efficient chain transferagent for methyl acrylate and that the process produces polymers of lowmolecular weight in a controlled manner.

Example 21

Preparation of Low Molecular Weight Olefin-Terminated Polymers of VinylAcetate Using Ethyl α-(t-Butanethiomethyl)acrylate

(Formula I, X=sulphur, R¹=—COOCH₂CH₃, R²=t-butyl, n=1).

Samples of poly(vinyl acetate) prepared in the manner of example 4 using4.8 mg, 11.6 mg, and 22.0 mg of ethyl α-(t-butanethiomethyl)acrylate hadnumber-average molecular weights of 61816, 12764, and 1598,respectively. These results show that ethylα-(t-butanethiomethyl)acrylate acts as a chain transfer agent for vinylacetate and that the process produces polymers of low molecular weight.

Example 22

Preparation of Low Molecular Weight α-Carboxy, ω-Unsaturated Polymers ofMethyl Methacrylate Using Ethyl α-(Carboxymethanethiomethyl)acrylate

(Formula I, X=sulphur, R^(1=—COOCR) ₂CH₃, R²=—CH₂COOH, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 9.8 mg, and 21.5 mg of ethylα-(carboxymethanethiomethyl)acrylate had number-average molecularweights of 164265, 74307, and 44473, respectively. The chain transferconstant calculated from these data was 0.73. These results show thatethyl α-(carboxymethanethiomethyl)acrylate is an efficient chaintransfer agent for methyl methacrylate and that the process producescarboxylic acid end-functional polymers of low molecular weight in acontrolled manner.

Example 23

Preparation of Low Molecular Weight α-Carboxy, ω-Unsaturated Polymers ofStyrene Using Ethyl α-(Carboxymethanethiomethyl)acrylate

(Formula I, X=sulphur, R¹=—COOCH₂CH₃, R²=—CH₂COOH, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,10.8 mg, 21.0 mg, and 40.2 mg of ethylα-(carboxymethanethiomethyl)acrylate had number-average molecularweights of 113921, 37477, 20894, and 12076, respectively. The chaintransfer constant calculated from these data was 1.72. These resultsshow that ethyl α-(carboxymethanethiomethyl)acrylate is an efficientchain transfer agent for styrene and that the process producescarboxylic acid end-functional polymers of low molecular weight in acontrolled manner. A sample of polystyrene produced similarly using 186mg of the chain transfer agent was precipitated two further times fromtoluene/methanol to remove traces of the unreacted chain transfer agent.The resulting polymer of number-average molecular weight 4014 hadsignals at δ 1.15, 3.9-4.1, 5.0-5.1, and 5.8-5.9 in the ¹H NMR spectrumconfirming the presence of an ethyl ester and a terminal double bond.Integration of the spectrum showed that one each of these groups waspresent per polymer chain. The infrared spectrum of the polymer showedabsorptions at 3500-2300 (broad), 1705 (broad) and 1295 cm⁻¹ consistentwith the presence of a carboxylic acid group.

Example 24

Preparation of Low Molecular Weight α,ω-Dicarboxy, ω-UnsaturatedPolymers of Methyl Methacrylate Usingα-(Carboxymethanethiomethyl)acrylic Acid (Formula I, X=sulphur,R¹=—COOH, R²=—CH₂COOH, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 10.0 mg, 20.2 mg, and 40.0 mg ofα-(carboxymethanethiomethyl)acrylic acid had number-average molecularweights of 154487, 69520, 40763, and 24084, respectively. The chaintransfer constant calculated from these data was 0.74. These resultsshow that α-(carboxymethanethiomethyl)acrylic acid is an efficient chaintransfer agent for methyl methacrylate and that the process produces lowmolecular weight polymers having carboxylic acid groups at both ends.

Example 25

Preparation of Low Molecular Weight α,ω-Dicarboxy, α-UnsaturatedPolymers of Styrene Using α-(Carboxymethanethiomethyl)acrylic Acid

(Formula I, X=sulphur, R¹=—COOH, R²=—CH₂COOH, n=1).

Azobisisobutyronitrile (34.3 mg) was dissolved in freshly distilledstyrene (25 ml). Acetone (25 ml) was added to ensure that the chaintransfer agent was soluble. Aliquots (10 ml) were removed and added toampoules containing the amount of the chain transfer agent shown below.The mixtures were polymerized and examined as per example 2. Samples ofpolystyrene prepared using 0 mg, 10.1 mg, 20.3 mg, and 40.2 mg ofα-(carboxymethanethiomethyl)acrylic acid had number-average molecularweights of 53361, 28162, 19652, and 12118, respectively. The chaintransfer constant calculated from these data was 1.27. These resultsshow that α-(carboxymethanethiomethyl)acrylic acid is an efficient chaintransfer agent for styrene and that the process produces low molecularweight polymers having a carboxylic acid group at both ends. The polymerof number-average molecular weight 12118, was precipitated two furthertimes from toluene/methanol to remove traces of the chain transferagent. The IR spectrum showed absorptions at 1735 and at 1700 cm⁻¹confirming the presence of the saturated and α,β-unsaturated carboxylicacid groups at the ends of the polymer chain.

Example 26

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using α-(t-Butanethiomethyl)acrylonitrile

(Formula I, X=sulphur, R¹=—CN, R²=t-butyl, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 10.5 mg, 19.9 mg, and 38.3 mg ofα-(t-butanethiomethyl)acrylonitrile had number-average molecular weightsof 181352, 35500, 23769, and 12724, respectively. The chain transferconstant calculated from these data was 1.36. These results show thatα-(t-butanethiomethyl)acrylonitrile is an efficient chain transfer agentfor methyl methacrylate and that the process produces polymers of lowmolecular weight in a controlled manner.

Example 27

Preparation of Low Molecular Weight Olefin-Terminated Polymers ofStyrene Using α-(t-Butanethiomethyl)acrylonitrile (Formula I, X=sulphur,R¹=—CN, R²=t-butyl, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,10.5 mg, and 30.6 mg of α-(t-butanethiomethyl)acrylonitrile hadnumber-average molecular weights of 118703, 29783, and 11747,respectively. The chain transfer constant calculated from these data was1.75. These results show that α-(t-butanethiomethyl)acrylonitrile is anefficient chain transfer agent for styrene and that the process producespolymers of low molecular weight in a controlled manner. A sample ofpolystyrene produced similarly using 200 mg of the chain transfer agentwas precipitated two further times from ethyl acetate/methanol to removetraces of the unreacted chain transfer agent. The resulting polymer ofnumber-average molecular weight 5491 had signals at δ 5.3-5.4 in the ¹HNMR spectrum confirming the presence of a terminal double bond.Integration of the spectrum showed that one of these groups was presentper polymer chain. The infrared spectrum of the polymer showed anabsorption at 2220 cm⁻¹ confirming the presence of a cyano group.

Example 28

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylAcrylate Using α-(t-Butanethiomethyl)acrylonitrile

(Formula I, X=sulphur, R¹=—CN, R²=t-butyl, n=1).

Samples of poly(methyl acrylate) prepared in the manner of example 3using 0 mg, 8.0 mg, 12.1 mg, and 16.1 mg ofα-(t-butanethiomethyl)acrylonitrile had number-average molecular weightsof 224288, 37084, 26347, and 21079, respectively. The chain transferconstant calculated from these data was 1.64. These results show thatα-(t-butanethiomethyl)acrylonitrile is an efficient chain transfer agentfor methyl acrylate and that the process produces polymers of lowmolecular weight in a controlled manner.

Example 29

Preparation of Low Molecular Weight Olefin-Terminated Polymers of VinylAcetate Using α-(t-Butanethiomethyl)acrylonitrile

(Formula I, X=sulphur, R¹=CN, R²=t-butyl, n=1).

Samples of poly(vinyl acetate) prepared in the manner of example 4 using0 mg, 5.6 mg, 10.7 mg, and 22.1 mg ofα-(t-butanethiomethyl)acrylonitrile had number-average molecular weightsof 243721, 10438, 2905, and 1079, respectively. The chain transferconstant calculated from these data was 60. These results show thatα-(t-butanethiomethyl)acrylonitrile acts as a chain transfer agent forvinyl acetate and that the process produces polymers of low molecularweight.

Example 30

Preparation of Low Molecular Weight α-Bromo, ω-Unsaturated Polymers ofMethyl Methacrylate Using Ethyl α-(Bromomethyl)acrylate

(Formula I, X=Br, R¹=—COOCH₂CH₃, n=0).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 26.62 mg, and 51.33 mg of ethyl α-(bromomethyl)acrylate hadnumber-average molecular weights of 220453, 20690, and 11668,respectively. The chain transfer constant calculated from these data was1.45. These results show that ethyl α-(bromomethyl)acrylate is anefficient chain transfer agent for methyl methacrylate and that theprocess produces bromine end-functional polymers of low molecular weightin a controlled manner.

Example 31

Preparation of Low Molecular Weight α-Bromo, ω-Unsaturated Polymers ofMethyl Acrylate Using Ethyl α-(Bromomethyl)acrylate

(Formula I, X=Br, R¹=—COOCH₂CH₃, n=0).

Samples of poly(methyl acrylate) prepared in the manner of example 3using 0 mg and 31.3 mg of ethyl α-(bromomethyl)acrylate hadnumber-average molecular weights of 496642 and 9888, respectively. Thechain transfer constant calculated from these data was 2.33. Theseresults show that ethyl α-(bromomethyl)acrylate is an efficient chaintransfer agent for methyl acrylate and that the process producespolymers of low molecular weight.

Example 32

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using α-(Diethyoxyphosphonylmethyl)styrene

(Formula I, X=P(O), R¹=phenyl, R²=ethoxy, n=2).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 11.4 mg, 22.6 mg, and 43.8 mg ofα-(diethoxyphosphorylmethyl)styrene had number-average molecular weightsof 210866, 124132, 88457, and 63441, respectively. The chain transferconstant calculated from these data was 0.35. These results show thatα-(diethoxyphosphorylmethyl)styrene is an efficient chain transfer agentfor methyl methacrylate and that the process produces polymers of lowmolecular weight in a controlled manner.

Example 33

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using Ethyl α-(Trimethylsilylmethyl)acrylate

(Formula I, X=Si, R¹=—COOCH₂CH₃, R²=methyl, n=3).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg and 19.4 mg of ethyl α-(trimethylsilylmethyl)acrylate hadnumber-average molecular weights of 181352 and 137986, respectively. Thechain transfer constant calculated from these data was 0.08. Theseresults show that ethyl α-(trimethylsilylmethyl)acrylate acts as a chaintransfer agent for methyl methacrylate and that the process producespolymers of lowered molecular weight.

Example 34

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using Ethyl α-(Tri-n-butylstannylmethyl)acrylate

(Formula I, X=Sn, R¹=—COOCH₂CH₃, R²=n-butyl, n=3).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 12.6 mg, 23.0 mg, and 37.7 mg of ethylα-(tri-n-butylstannylmethyl)acrylate had number-average molecularweights of 196981, 36232, 22349, and 15473, respectively. The chaintransfer constant calculated from these data was 3.01. These resultsshow that ethyl α-(tri-n-butylstannylmethyl)acrylate is an efficientchain transfer agent for methyl methacrylate and that the processproduces polymers of low molecular weight in a controlled manner.

Example 35

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using Ethyl α-(Benzenesulphonylmethyl)acrylate

(Formula I, X=S(O)₂, R¹ —COOCH₂CH₃, R²=phenyl, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 10.3 mg, 20.1 mg, and 30.0 mg of ethylα-(benzenesulphonylmethyl)acrylate had number-average molecular weightsof 181352, 64607, 38949, and 29612, respectively. The chain transferconstant calculated from these data was 1.14. These results show thatethyl α-(benzenesulphonylmethyl)acrylate is an efficient chain transferagent for methyl methacrylate and that the process produces polymers oflow molecular weight in a controlled manner.

Example 36

Preparation of Low Molecular Weight Olefin-Terminated Polymers ofStyrene Using Ethyl α-(Benzenesulphonylmethyl)acrylate

(Formula I, X=(O)₂, R¹=—COOCH₂CH₃, R²=phenyl, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,10.9 mg, 20.4 mg, and 40.1 mg of ethylα-(benzenesulphonylmethyl)acrylate had number-average molecular weightsof 112707, 15520, 9099, and 4728, respectively. The chain transferconstant calculated from these data was 5.75. These results show thatethyl α-(benzenesulphonylmethyl)acrylate is an efficient chain transferagent for styrene and that the process produces polymers of lowmolecular weight in a controlled manner. The sample of polystyrene ofnumber-average molecular weight 4728 was precipitated two further timesfrom ethyl acetate/methanol to remove traces of the unreacted chaintransfer agent. The resulting polymer had signals at δ5.0-5.1, and5.8-5.9 in the ¹H NMR spectrum confirming the presence of the terminaldouble bond.

Example 37

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using α-(n-Butanesulphinylmethyl)styrene

(Formula I, X=S(O), R¹=phenyl, R²=n-butyl, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 10.2 mg, and 20.3 mg of ethylα-(n-butanesulphinylmethyl)styrene had number-average molecular weightsof 236818, 40155, and 24323, respectively. The chain transfer constantcalculated from these data was 1.89. These results show that ethyld-(n-butaneaulphinylmethyl)styrene is an efficient chain transfer agentfor methyl methacrylate and that the process produces polymers of lowmolecular weight.

Example 38

Preparation of Low Molecular Weight Olefin-TerminatedPolymers of MethylMethacrylate Using α-(Benzenesulphonylmethyl)vinyl Acetate

(Formula I, X=S(O)₂, R¹=—OAc, R²=phenyl, n=1).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 27.3 mg, 49.0 mg, and 100.8 mg ofα-(benzenesulphonylmethyl)vinyl acetate had number-average molecularweights of 269320, 194204, 163144, and 104847, respectively. The chaintransfer constant calculated from these data was 0.065. These resultsshow that α-(benzenesulphonylmethyl)vinyl acetate acts as a chaintransfer agent for methyl methacrylate and that the process producespolymers of low molecular weight in a controlled manner.

Example 39

Preparation of Low Molecular Weight Olefin-Terminated Polymers ofStyrene Using α-(Benzenesulphonylmethyl)vinyl Acetate

(Formula I, X=S(O)₂, R¹=—OAc, R²=phenyl, n=1).

Samples of polystyrene prepared in the manner of example 2 using 0 mg,20.0 mg, 40.0 mg, and 80.4 mg of α-(benzenesulphonylmethyl)vinyl acetatehad number-average molecular weights of 105213, 102276, 97437, and89049, respectively. The chain transfer constant calculated from thesedata was 0.02. These results show that α-(benzenesulphonylmethyl)vinylacetate acts as a chain transfer agent for styrene and that the processproduces polymers of low molecular weight in a controlled manner.

Example 40

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylAcrylate Using α-(Benzenesulphonylmethyl)vinyl Acetate

(Formula I, X=S(O)₂, R¹=—OAc, R²=phenyl, n=1).

Samples of poly(methyl acrylate) prepared in the manner of example 3using 22.8 mg, 50.0 mg, and 99.4 mg of α-(benzenesulphonylmethyl)vinylacetate had number-average molecular weights of 107713, 73613, and40108, respectively. The chain transfer constant calculated from thesedata was 0.20. These results show that α-(benzenesulphonylmethyl)vinylacetate is an efficient chain transfer agent for methyl acrylate andthat the process produces polymers of low molecular weight in acontrolled manner.

Example 41

Preparation of Low Molecular Weight Olefin-Terminated Polymers of VinylAcetate Using α-(Benzenesulphonylmethyl)vinyl Acetate

(Formula I, X=S(O)₂, R¹=—OAc, R²=phenyl, n=1).

Samples of poly(vinyl acetate) prepared in the manner of example 4 using0 mg, 5.1 mg, 10.3 mg, and 20.5 mg of α-(benzenesulphonylmethyl)vinylacetate had number-average molecular weights of 144664, 113338, 64712,and 39212, respectively. The chain transfer constant calculated fromthese data was 2.8. These results show thatα-(benzenesulphonylmethyl)vinyl acetate is an efficient chain transferagent for vinyl acetate and that the process produces polymers of lowmolecular weight in a controlled manner.

Example 42

Preparation of Low Molecular Weight α-Bromo, ω-Unsaturated Polymers ofMethyl Methacrylate Using α-(Bromomethyl)acrylonitrile

(Formula I, X=Br, R¹=—CN, n=0).

Samples of poly(methyl methacrylate) prepared in the manner of example 5using 0 mg, 24.0 mg, 49.0 mg, and 99.8 mg ofα-(bromomethyl)acrylonitrile had number-average molecular weights of234433, 10029, 5263, and 3124, respectively. The chain transfer constantcalculated from these data was 2.22. These results show thatα-(bromomethyl)acrylonitrile is an efficient chain transfer agent formethyl methacrylate and that the process produces polymers of lowmolecular weight in a controlled manner.

Example 43

Preparation of Low Molecular Weight α-Bromo, ω-Unsaturated Polymers ofMethyl Acrylate Using α-(Bromomethyl)acrylonitrile

(Formula I, X=Br, R¹=—CN, n=0).

Samples of poly(methyl acrylate) prepared in the manner of example 5using 22.8 mg, 50.0 mg, and 99.4 mg of d-(bromomethyl)acrylonitrle hadnumber-average molecular weights of 107713, 73613, and 40108,respectively. The chain transfer constant calculated from these data was3.0. These results show that α-(bromomethyl)acrylonitrile is anefficient chain transfer agent for methyl acrylate and that the processproduces polymers of low molecular weight in a controlled manner.

Example 44

Preparation of Low Molecular Weight α-Chloro, ω-Unsaturated Polymers ofMethyl Acrylate Using α-(Chloromethyl)acrylonitrile

(Formula I, X=Cl, R¹=—CN, n=0).

Samples of poly(methyl acrylate) prepared in the manner of example 3using 0 mg, 11.8 mg, 24.8 mg, and 50.8 mg ofα-(chloromethyl)acrylonitrile had number-average molecular weights of502537, 232619, 158821, and 74136, respectively. The chain transferconstant calculated from these data was 0.05. These results show thatα-(chloromethyl)acrylonitrile acts as a chain transfer agent for methylacrylate and that the process produces polymers of low molecular weightin a controlled manner.

Example 45

Preparation of Low Molecular Weight Polyacrylonitrile Usingα-(t-Butanethiomethyl)acrylonitrile

(Formula I, X=sulphur, R¹=—CN, R²=t-butyl, n=1).

Azobisisobutyronitrile (7.4 mg) was dissolved in freshly distilledacrylonitrile (10 ml). An aliquot (2 ml) was removed and added toα-(t-butanethiomethyl)acrylonitrile (14.5 mg) and the mixture waspolymerized in the absence of oxygen for 1 h at 60° C. The resultingpolymer was precipitated in toluene. A portion (100 mg) of the driedpolymer was dissolved in dimethylformamide (10 ml) and the viscosity wasmeasured using a Gardiner Bubble viscometer. The resulting polymer had aviscosity less than that of tube B. A similar polymer prepared withoutadded chain transfer agent had a viscosity equal to that of tube E. Thisresult shows that the polymer prepared usingα-(t-butanethiomethyl)acrylonitrile had a lower molecular weight thanthat prepared without, and that α-(t-butanethiomethyl)acrylonitrile actsas a chain transfer agent for acrylonitrile.

Example 46

Preparation of Low Molecular Weight Polyacrylonitrile Usingα-(t-Butanethiomethyl)styrene

(Formula I, X=sulphur, R¹=phenyl, R²=t-butyl, n=1).

A polymer prepared as above (Example 45) usingα-(t-butanethiomethyl)styrene (15.6 mg) was precipitated in toluene. Aportion (100 mg) of the dried polymer was dissolved in dimethylformamide(10 ml) and the viscosity was measured using a Gardiner Bubbleviscometer. The resulting polymer had a viscosity less than that of tubeB. A similar polymer prepared without added chain transfer agent had aviscosity equal to that of tube E. This result shows that the polymerprepared using α-(t-butanethiomethyl)styrene had a lower molecularweight than that prepared without, and thatα-(t-butanethiomethyl)styrene acts as a chain transfer agent foracrylonitrile.

Example 47

Preparation of Low Molecular Weight Polymers of Methyl Methacrylate(MMA) Using α-Benzyloxystyrene

(Formula II, R¹=phenyl, R² =benzyl).

Azobisisobutyronitrile (19.4 mg) was dissolved in freshly distilledmethyl methacrylate (10.00 ml). An aliquot (2.00 ml) was removed andadded to an ampoule containing the amount of the chain transfer agent,α-benzyloxystyrene, shown in Table II. The mixture was polymerized at60° C. for 1 h in the absence of oxygen. The contents of the ampoulewere then poured into pentane and the precipitated polymer was collectedand dried in vacuo to constant weight. A small portion was examined byGPC using a Waters Instrument connected to six v-Styragel columns (10⁶-,10⁵-, 10³-, 500- and 100-Å pore size). Tetrahydrofuran was used aseluent and the system was calibrated using narrow distributionpolystyrene standards (Waters).

TABLE II α-Benzyloxystyrene % added (mg)$\frac{\lbrack {\alpha - {Benzyloxystyrene}} \rbrack}{\lbrack{Styrene}\rbrack}$

{overscore (M)}_(n)* Conversion 0  0 207,000  11.8  4.0 1.02 × 10⁻³96,564 12.2 10.3 2.62 × 10⁻³ 41,395 10.1 15.8 4.02 × 10⁻³ 28,123 11.022.0 5.60 × 10⁻³ 21,275 10.7 25.3 6.44 × 10⁻³ 18,688 10.6 37.0 9.42 ×10⁻³ 13,397 10.0 41.0 1.04 × 10⁻² 11,849 12.1 48.0 1.22 × 10⁻² 10,38010.0 *Polystyrene-equivalent number-average molecular weight, obtainedby GPC.

The chain transfer constant calculated from these data was 0.76, whichcompares favourably with that from n-butanethiol (chain transferconstant=0.66). These results show that α-benzyloxystyrene is anefficient chain transfer agent for methyl methacrylate and that theprocess produces polymers of low molecular weight in a controlledmanner.

Example 48

Preparation of Low Molecular Weight Polymers of Styrene Usingα-Benzyloxystyrene

(Formula II, R¹=phenyl, R²=benzyl).

Azobisisobutyronitrile (70.4 mg) was added to freshly distilled styrene(50 ml). An aliquot (10 ml) of this mixture was removed and added to anampoule containing the amount of benzyloxystyrene shown (Table III). Themixture was polymerized for 1 h at 60° C. in the absence of oxygen. Thecontents of the ampoule were then poured into methanol (110 ml) and theprecipitated polymer was collected, dried and examined by GPC asdescribed previously.

TABLE III α-Benzyloxystyrene % added (mg)$\frac{\lbrack {\alpha - {Benzyloxystyrene}} \rbrack}{\lbrack{Styrene}\rbrack}$

{overscore (M)}_(n) Conversion  0.0 0.00 137,320  2.8  44.5 2.43 × 10⁻³78,812 3.2  45.6 2.49 × 10⁻³ 78,010 2.9  49.1 2.68 × 10⁻³ 76,022 3.0 91.6 5.00 × 10⁻³ 50,674 2.4 144.9 7.91 × 10⁻³ 38,146 3.0 170.3 9.29 ×10⁻³ 32,928 3.4 231.4 1.26 × 10⁻² 26,802 3.0 261.5 1.43 × 10⁻² 23,4173.5

The chain transfer constant calculated from these data was 0.26, whichis closer to the ideal than that from n-butanethiol (chain transferconstant=22). These results show that α-benzyloxystyrene is an efficientchain transfer agent for styrene and that the process produces polymersof low molecular weight in a controlled manner.

Example 49

Preparation of Low Molecular Weight Polymers of Methyl Acrylate Usingα-Benzyloxystyrene

(Formula II, R¹=phenyl, R²=benzyl).

Azobisisobutyronitrile (8.0 mg) was dissolved in a mixture ofthiophenefree benzene (80 ml) and freshly distilled methyl acrylate (20ml). Aliquots (10 ml) were removed and added to ampoules containing theamounts of α-benzyloxystyrene shown below. The mixtures were thenpolymerized at 60° C. for 1 h in the absence of oxygen. The volatileswere then removed and the polymers were dried in vacuo to constantweight. The polymers were then examined by GPC as described above.Samples of poly(methyl acrylate) prepared in this manner using 0 mg, 4.8mg, and 10.2 mg of α-benzyloxystyrene had number-average molecularweights of 577200, 14652, and 6866, respectively. The chain transferconstant calculated from these data was 5.7. These results show thatα-benzyloxystyrene is an efficient chain transfer agent for methylacrylate and that the process produces polymers of low molecular weightin a controlled manner.

Example 50

Preparation of Low Molecular Weight Polymers of Vinyl Acetate Usingα-Benzyloxystyrene

(Formula II, R¹=phenyl, R²=benzyl).

Azobisisobutyronitrile (8.0 mg) was dissolved in freshly distilled vinylacetate (50 ml). Aliquots (10 ml) were removed and added to ampoulescontaining the amounts of α-benzyloxystyrene shown below. The mixtureswere then polymerized at 60° C. for 1 h in the absence of oxygen. Thevolatiles were then removed and the polymers were dried in vacuo toconstant weight. The polymers were then examined by GPC as describedabove. Samples of poly(vinyl acetate) prepared in this manner using 0mg, 2.3 mg, 5.1 mg, 10.0 mg, and 20.7 mg of α-benzyloxystyrene hadnumber-average molecular weights of 260760, 75723, 35337, 22116, and9458, respectively. The chain transfer constant calculated from thesedata was 9.7, which is closer to the ideal than that of n-butanethiol(chain transfer constant=48). These results show that α-benzyloxystyreneis an efficient chain transfer agent for vinyl acetate and that theprocess produces polymers of low molecular weight in a controlledmanner.

Example 51

Preparation of Low Molecular Weight Polymers of Methyl MethacrylateUsing α-Benzyloxyacrylonitrile

(Formula II, R¹=—CN, R²=benzyl).

Azobisisobutyronitrile (19.4 mg) was dissolved in freshly distilledmethyl methacrylate (10 ml). Aliquots (2 ml) were removed and added toampoules containing the amounts of α-benzyloxyacrylonitrile shown below.The mixtures were then polymerized at 60° C. for 1 h in the absence ofoxygen. The contents of the ampoules were added to separate portions ofpetroleum spirit (30 ml) and the preciptiated polymers were collectedand dried in vacuo to constant weight. The polymers were then examinedby GPC as described above. Samples of poly(methyl methacrylate) preparedin this manner using 0 mg, 10.0 mg, 12.4 mg, and 34.7 mg of0-benzyloxyacrylonitrile had number-average molecular weights of 200810,132040, 124140, and 69706, respectively. The chain transfer constantcalculated from these data was 0.082. These results show thatα-benzyloxyacrylonitrile acts as a chain transfer agent for methylmethacrylate and that the process produces polymers of lower molecularweight in a controlled manner.

Example 52

Preparation of Low Molecular Weight Polymers of Styrene Usingα-Benzyloxyacrylonitrile

(Formula II, R¹=—CN, R²=benzyl).

Samples of polystyrene prepared in the manner of example 48 using 42.8mg, 86.4 mg, and 153.2 mg of α-benzyloxyacrylonitrile had number-averagemolecular weights of 107460, 95028, and 83280, respectively. The chaintransfer constant calculated from these data was 0.038. These resultsshow that α-benzyloxyacrylonitrile acts as a chain transfer agent forstyrene and that the process produces polymers of controlled molecularweight.

Example 53

Preparation of Low Molecular Weight Polymers of Methyl Acrylate Usingα-Benzyloxyacrylonitrile

(Formula II, R¹=—CN, R²=benzyl).

Samples of poly(methyl acrylate) prepared in the manner of example 49using 0 mg, 10.4 mg, 40.0 mg, and 66.6 mg of α-benzyloxyacrylonitrilehas number-average molecular weights of 500000, 75781, 21018, and 14779,respectively. The chain transfer constant calculated from these data was0.30. These results show that α-benzyloxyacrylonitrile acts as anefficient chain transfer agent for methyl acrylate and that the processproduces polymers of low molecular weight in a controlled manner.

Example 54

Preparation of Low Molecular Weight Polymers of Vinyl Acetate Usingα-Benzyloxyacrylonitrile

(Formula II, R¹=—CN, R²=benzyl).

Samples of poly(vinyl acetate) prepared in the manner of example 50using 0 mg, 2.0 mg, and 20.0 mg of α-benzyloxyacrylonitrile hadnumber-average molecular weights of 225319, 46036, and 6032,respectively. The chain transfer constant calculated from these data was11. These results show that α-benzyloxyacrylonitrile acts as anefficient chain transfer agent for vinyl acetate and that the processproduces polymers of low molecular weight in a controlled manner.

Example 55

Preparation of Low Molecular Weight Polymers of Methyl MethacrylateUsing Methyl α-Benzyloxyacrylate

(Formula II, R¹=COOCH₃, R²=benzyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 7.9 mg, 16.3 mg, 26.3 mg, and 40.1 mg of methylα-benzyloxyacrylate had number-average molecular weights of 99822,73462, 55557, and 41633, respectively. The chain transfer constantcalculated from these data was 0.16. These results show that methylα-benzyloxyacrylate acts as a chain transfer agent for methylmethacrylate and that the process produces polymers of low molecularweight in a controlled manner.

Example 56

Preparation of Low Molecular Weight Polymers of Styrene is Using Methylα-Benzyloxyacrylate

(Formula II, R¹=COOCH₃, R²=benzyl).

Samples of polystyrene prepared in the manner of example 48 using 0 mg,20.2 mg, and 80.4 mg of methyl α-benzyloxyacrylate had number-averagemolecular weights of 106391, 92060, and 71658, respectively. The chaintransfer constant calculated from these data was 0.042. These resultsshow that methyl α-benzyloxyacrylate acts as a chain transfer agent forstyrene and that the process produces polymers of lower molecularweight.

Example 57

Preparation of Low Molecular Weight Polymers of Methyl Acrylate UsingMethyl α-Benzyloxyacrylate

(Formula II, R¹=—COOCH₃, R² =benzyl).

Samples of methyl acrylate prepared in the manner of example 49 using 0mg, 10.1 mg, 25.0 mg, and 60.2 mg of methyl α-benzyloxyacrylate hadnumber-average molecular weights of 442463, 41424, 18894, and 8964,respectively. The chain transfer constant calculated from these data was0.56. These results show that methyl α-benzyloxyacrylate acts as anefficient chain transfer agent for methyl acrylate and that the processproduces polymers of low molecular weight in a controlled manner.

Example 58

Preparation of Low Molecular Weight Polymers of Vinyl Acetate UsingMethyl α-Benzyloxyacrylate

(Formula II, R¹=COOCH₃, R² benzyl).

Samples of poly(vinyl acetate) prepared in the manner of example 50using 0 mg, 4.8 mg, 10.1 mg, and 20.2 mg of methyl α-benzyloxyacrylatehad number-average molecular weights of 245714, 17851, 8382, and 4252,respectively. The chain transfer constant calculated from these data was20.8. These results show that methyl α-benzyloxyacrylate acts as a chaintransfer agent for vinyl acetate and that the process produces polymersof low molecular weight in a controlled manner.

Example 59

Preparation of Low Molecular Weight Polymers of Methyl MethacrylateUsing α-Benzyloxyacrylamide

(Formula II, R¹=—CONH₂, R²=benzyl.

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 7.3 mg, 15.2 mg, 25.3 mg, and 40.3 mg of α-benzyloxyacrylamidehad number-average molecular weights of 57642, 36026, 23419, and 15687,respectively. The chain transfer constant calculated from these data was0.47. These results show that α-benzyloxyacrylamide acts as an efficientchain transfer agent for methyl methacrylate and that the processproduces polymers of low molecular weight in a controlled manner.

Example 60

Preparation of Low Molecular Weight Polymers of Styrene Usingα-Benzyloxyacrylamide

(Formula II, R¹=—CONH₂, R² =benzyl).

Samples of polystyrene prepared in the manner of example 48 using 0 mg,20.1 mg, 39.6 mg, and 80.6 mg of α-benzyloxyacrylamide hadnumber-average molecular weights of 66537, 48539, 42313, and 33687,respectively. The chain transfer constant calculated from these data was0.13. These results show that α-benzyloxyacrylamide acts as a chaintransfer agent for styrene and that the process produces polymers of lowmolecular weight in a controlled manner.

Example 61

Preparation of Low Molecular Weight Polymers of Methyl Acrylate Usingα-Benzyloxyacrylamide

(Formula II, R¹=—CONH₂, R²=benzyl).

Samples of poly(methyl acrylate) prepared in the manner of example 49using 0 mg, 9.8 mg, 24.7 mg, and 58.2 mg of α-benzyloxyacrylamide hadnumber-average molecular weights of 529892, 26913, 11193, and 5431,respectively. The chain transfer constant calculated from these data was1.10. These results show that α-benzyloxyacrylamide acts as an efficientchain transfer agent for methyl acrylate and that the process producespolymers of low molecular weight in a controlled manner.

Example 62

Preparation of Low Molecular Weight Olefin-Terminated Polymers of MethylMethacrylate Using α-Allyloxystyrene

(Formula II, R¹=phenyl, R²=allyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 14.6 mg, and 30.1 mg of α-allyloxystyrene hadnumber-average molecular weights of 238380, 28873, and 14953,respectively. The chain transfer constant calculated from these data was0.62. These results show that α-allyloxystyrene acts as an efficientchain transfer agent for methyl methacrylate and that the processproduces polymers of low molecular weight. A sample of poly(methylmethacrylate) produced similarly using 294 mg of α-allyloxystyrene wasprecipitated two further times from ethyl acetate/pentane to removetraces of the unreacted chain transfer agent. The resulting polymer ofnumber-average molecular weight 2418 had signals at δ 4.8-5.0 and at δ5.5-5.8 in the ¹H NMR spectrum confirming the presence of a terminaldouble bond. Integration of the spectrum showed that one of these groupswas present per polymer chain.

Example 63

Preparation of Low Molecular Weight Olefin-Terminated Polymers ofStyrene Using α-Allyloxystyrene

(Formula II, R¹=phenyl, R² =allyl).

Samples of polystyrene prepared in the manner of example 48 using 0 mg,97.0 mg, and 197.0 mg of α-allyloxystyrene had number-average molecularweights of 137320, 53106, and 31889, respectively. The chain transferconstant calculated from these data was 0.18. These results show thatα-allyloxystyrene acts as an efficient chain transfer agent for styreneand that the process produces polymers of low molecular weight in acontrolled manner.

Example 64

Preparation of Low Molecular Weight Polymers of Methyl -MethacrylateUsing α-Isopropyloxystyrene

(Formula II, R¹=phenyl, R²=isopropyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 20.5 mg, and 39.1 mg of α-isopropyloxystyrene hadnumber-average molecular weights of 247208, 48601, and 26986,respectively. The chain transfer constant calculated from these data was0.25. These results show that α-isopropyloxystyrene acts as a chaintransfer agent for methyl methacrylate and that the process producespolymers of low molecular weight in a controlled manner.

Example 65

Preparation of Low Molecular Weight Polymers of Methyl MethacrylateUsing α-Methoxystyrene

(Formula II, R¹=phenyl, R²=methyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 17.0 mg, and 32.4 mg of α-methoxystyrene hadnumber-average molecular weights of 240673, 198460, and 151800,respectively. The chain transfer constant calculated from these data was0.02. These results show that α-methoxystyrene acts as a chain transferagent for methyl methacrylate and that the process produces polymers oflower molecular weight.

Example 66

Preparation of Ester-Terminated Low Molecular Weight Polymers of StyreneUsing α-(4-Methoxycarbonylbenzyloxy)styrene

(Formula II, R¹=phenyl, R²=4-CH₃OC(O)C₆H₄CH₂—).

Samples of polystyrene prepared in the manner of example 48 using 0 mg,132.1 mg, and 267.4 mg of α-(4-methoxycarbonylbenzyloxy)styrene hadnumber-average molecular weights of 137000, 51580, and 31553,respectively. The chain transfer constant calculated from these data was0.22. These results show that α-(4-methoxycarbonylbenzyloxy)styrene actsas a chain transfer agent for styrene and that the process producespolymers of lower molecular weight. A sample of polystyrene producedsimilarly using 745 mg of α-(4-methoxycarbonylbenzyloxy)styrene wasprecipitated two further times from ethyl acetate/methanol to removetraces of the unreacted chain transfer agent. The resulting polymer ofnumber-average molecular weight 8298 had signals at δ 3.83 in the ¹R NMRspectrum confirming the presence of the methyl ester group. Integrationof the spectrum showed that one of these groups was present per polymerchain. The infrared spectrum of the polymer showed an absorption at 1720cm⁻¹, also confirming the presence of an ester group. The polymer couldbe hydrolysed by methods well known to the art to give a polymerterminated at one end with a carboxylic acid group.

Example 67

Preparation of Ester-Terminated Low Molecular Weight Polymers of MethylMethacrylate Using α-(4-Methoxycarbonylbenzyloxy)styrene

(Formula II, R¹=phenyl, R²=4-CH₃OC(O)C₆H₄CH₂—).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 26.4 mg, and 44.1 mg ofα-(4-methoxycarbonylbenzyloxy)styrene had number-average molecularweights of 246550, 24429, and 14955, respectively. The chain transferconstant calculated from these data was 0.70. These results show thatα-(4-methoxycarbonylbenzyloxy)styrene acts as a chain transfer agent formethyl methacrylate and that the process produces ester-terminatedpolymers of low molecular weight.

Example 68

Preparation of Low Molecular Weight Hydroxy-Terminated Polymers ofMethyl Methacrylate Using α-[4-(Hydroxymethyl)benzyloxy]styrene

(Formula II, R¹=phenyl, R²=HOCH₂C₆H₄CH₂—).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 9.9 mg, 19.8 mg, and 39.9 mg ofα-[4-(hydroxymethyl)benzyloxy]styrene had number-average molecularweights of 189492, 95120, 41752, and 20829, respectively. The chaintransfer constant calculated from these data was 0.5. These results showthat α-[4-(hydroxymethyl)benzyloxy]styrene acts as an efficient chaintransfer agent for methyl methacrylate and that the process producespolymers of low molecular weight in a controlled manner. A sample ofpoly(methyl methacrylate) produced similarly using 436 mg ofα-[4-(hydroxymethyl)benzyloxy]styrene was precipitated two further timesfrom ethyl acetate/pentane to remove traces of the unreacted chaintransfer agent. The resulting polymer of number-average molecular weight1764 had signals at 6 4.52 in the ¹H NMR spectrum confirming thepresence of a (hydroxymethyl)phenyl group. Integration of the spectrumshowed that one of these groups was present per polymer chain.

Example 69

Preparation of Low Molecular Weight Hydroxy-Terminated Polymers ofStyrene Using α-[4-(Hydroxymethyl)benzyloxy]styrene

(Formula II, R¹=phenyl, R²=H HOCH₂C₆H₄CH₂—).

Samples of polystyrene prepared in the manner of example 48 using 0 mg,20.1 mg, 40.1 mg, and 80.3 mg of M-[4-(hydroxymethyl)benzyloxy]styrenehad number-average molecular weights of 112326, 76147, 56570, and 37926,respectively. The chain transfer constant calculated from these data was0.24. These results show that α-[4-(hydroxymethyl)benzyloxylstyrene actsas an-efficient chain transfer agent for styrene and that the processproduces polymers of low molecular weight in a controlled manner. Asample of polystyrene produced similarly using 1.30 g ofα-[4-(hydroxymethyl)benzyloxylstyrene was precipitated two further timesfrom ethyl acetate/methanol to remove traces of the unreacted chaintransfer agent. The resulting polymer of number-average molecular weight10239 had signals at δ 4.50 in the ¹H NMR spectrum confirming thepresence of a (hydroxymethyl)phenyl group. Integration of the spectrumshowed that one of these groups was present per polymer chain.

Example 70

Preparation of Low Molecular Weight Hydroxy-Terminated Polymers ofMethyl Acrylate Using α-[4-(Hydroxymethyl)benzyloxy]styrene

(Formula II, R¹=phenyl, R²=HOCH₂C₆H₄CH₂—).

Samples of poly(methyl acrylate) prepared in the manner of example 49using 0 mg, 11.7 mg, and 25.3 mg ofα-[4-(hydroxymethyl)benzyloxyl]styrene had number-average molecularweights of 358538, 7064, and 3222, respectively. The chain transferconstant calculated from these data was 5.5. These results show thatα-[4-(hydroxymethyl)benzyloxy]styrene acts as an efficient chaintransfer agent for methyl acrylate and that the process producespolymers of low molecular weight in a controlled manner. A sample ofpoly(methyl acrylate) produced similarly using 41.6 mg ofα-[4-(hydroxymethyl)benzyloxy]styrene was precipitated five furthertimes from ethyl acetate/methanol and once from ethyl acetate/pentane atlow temperature to remove traces of the unreacted chain transfer agent.The resulting polymer of number-average molecular weight 15548 hadsignals at δ 4.53 in the ¹H NMR spectrum confirming the presence of a(hydroxymethyl)phenyl group. Integration of the spectrum showed that oneof these groups was present per polymer chain.

Example 71

Preparation of Low Molecular Weight Hydroxy-Terminated Polymers of VinylAcetate Using α-[4-(Hydroxymethyl)benzyloxy]styrene]

(Formula II, R¹=phenyl, R²=HOCH₂C₆H₄CH₂—).

Samples of poly(vinyl acetate) prepared in the manner of example 50using 0 mg, 4.9 mg, 10.2 mg, and 20.0 mg ofα-[4-(hydroxymethyl)benzyloxy]styrene had number-average molecularweights of 291871, 44164, 25185, and 11349, respectively. The chaintransfer constant calculated from these data was 9.0. These results showthat α-[4-(hydroxymethyl)benzyloxy]styrene acts as an efficient chaintransfer agent for vinyl acetate and that the process produceshydroxy-terminated polymers of low molecular weight in a controlledmanner.

Example 72

Preparation of Low Molecular Weight Nitrile-Terminated Polymers ofMethyl Methacrylate Using α-(4-Cyanobenzyloxy)styrene

(Formula II, R¹=phenyl, R²=NCC₆H₄CH₂=).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 10.0 mg, 21.8 mg, and 42.6 mg ofα-(4-cyanobenzyloxy)styrene had number-average molecular weights of242138, 46269, 26366, and 14551, respectively. The chain transferconstant calculated from these data was 0.77. These results show thatα-(4-cyanobenzyloxy)styrene acts as an efficient chain transfer agentfor methyl methacrylate and that the process produces nitrile-terminatedpolymers of low molecular weight in a controlled manner.

Example 73

Preparation of Low Molecular Weight Nitrile-Terminated Polymers ofStyrene Using α-(4-Cyanobenzyloxy)styrene

(Formula II, R¹=phenyl, R²=NCC₆H₄CH₂—).

Samples of polystyrene prepared in the manner of example 48 using 0 mg,40.0 mg, and 81.0 mg of α-(4-cyanobenzyloxy)styrene had number-averagemolecular weights of 107520, 75745, and 58482, respectively. The chaintransfer constant calculated from these data was 0.21. These resultsshow that α-(4-cyanobenzyloxy)styrene acts as an efficient chaintransfer agent for styrene and that the process produces polymers of lowmolecular weight in a controlled manner. The infrared spectrum of thepolymer showed an absorption at 2220 cm ¹ confirming the presence of anitrile group.

Example 74

Preparation of Low Molecular Weight Methoxy-Terminated Polymers ofMethyl Methacrylate Using α-(4-Methoxybenzyloxy)styrene

(Formula II, R¹=phenyl, R²=CH₃OC₆R₄CH₂—).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 15.9 mg and 39.4 mg of α-(4-methoxybenzyloxy)styrene hadnumber-average molecular weights of 37329 and 16096, respectively. Thechain transfer constant calculated from these data was 0.66. Theseresults show that α-(4-methoxybenzyloxy)styrene acts as an efficientchain transfer agent for methyl methacrylate and that the processproduces methoxy-terminated polymers of low molecular weight in acontrolled manner.

Example 75

Preparation of Low Molecular Weight Methoxy-Terminated Polymers ofStyrene Using α-(4-Methoxybenzyloxy)styrene

(Formula II, R¹=phenyl, R²=CH₃OC₆H₄CH₂—).

Samples of polystyrene prepared in the manner of example 48 using 122.3mg and 263.4 mg of α-(4-methoxybenzyloxy)styrene had number-averagemolecular weights of 56648 and 33395, respectively. The chain transferconstant calculated from these data was 0.19. These results show thatα-(4-methoxybenzyloxy)styrene acts as an efficient chain transfer agentfor styrene and that the process produces methoxy-terminated polymers oflow molecular weight in a controlled manner.

Example 76

Preparation of Low Molecular Weight Amine-Terminated Polymers of MethylMethacrylate Using α-[4-(Aminomethyl)benzyloxy]styrene

(Formula II, R¹=phenyl, R²=H₂NCH₂C₆R₄CH₂—).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 11.2 mg, 20.9 mg, and 39.8 mg ofα-[4-(aminomethyl)benzyloxy]styrene had number-average molecular weightsof 262866, 24717, 16088, and 7115, respectively. The chain transferconstant calculated from these data was 1.54. These results show thatα-[4-(aminomethyl)benzyloxy]styrene acts as an efficient chain transferagent for methyl methacrylate and that the process producesamine-terminated polymers of low molecular weight in a controlledmanner.

Example 77

Preparation of Low Molecular Weight (Chloromethyl)phenyl-TerminatedPolymers of Methyl Methacrylate Using a Mixture ofα-Benzyloxy[4-(chloromethyl)styrene] andα-Benzyloxy[3-(chloromethyl)styrene]

(Formula II, R¹=ClCH₂C₆R₄—, R²=benzyl—).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 25.3 mg, 44.1 mg, and 72.8 mg ofα-benzyloxy[4-(chloromethyl)styrene] andα-benzyloxy[3-(chloromethyl)styrene] had number-average molecularweights of 246550, 35572, 23907, and 17418, respectively. The chaintransfer constant calculated from these data was 0.44. These resultsshow that α-benzyloxy[(chloromethyl)styrene]acts as an efficient chaintransfer agent for methyl methacrylate and that the process producespolymers of low molecular weight in a a controlled manner. A sample ofpoly(methyl methacrylate) produced similarly using 300 mg of the chaintransfer agent was precipitated two further times from ethylacetate/pentane to remove traces of the unreacted chain transfer agent.The resulting polymer of number-average molecular weight 8034 hadsignals at δ 4.67 in the ¹ ¹H NMR spectrum confirming the presence of a(chloromethyl)phenyl group. Polymers terminated with this benzylicchloride group react with a variety of nucleophiles to give products inwhich the chlorine atom is replaced by the nucleophile. For example,reaction with cyanate ion leads to polymers terminated with anisocyanate group.

Example 78

Preparation of Low Molecular Weighttert-Butyldimethylsilyloxy-Terminated Polymers of Methyl MethacrylateUsing α-Benzyloxy[4-(tert-butyldimethylsilyloxymethyl)styrene]andα-Benzyloxy[3-(tert-butyldimethylsilyloxymethyl)styrene]

(Formula II, R¹=(tert-butyldimethylsilyloxymethyl)phenyl, R²=benzyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 38.8 mg, 72.4 mg, and 117.3 mg of a mixture ofα-benzyloxy[4-(tert-butyldimethylsilyloxymethyl)styrene] andα-benzyloxy[3-(tert-butyldimethylsilyloxymethyl)styrene] hadnumber-average molecular weights of 27555, 13147 and 8436, respectively.The chain transfer constant calculated from these data was 0.66. Theseresults show that the compounds act as efficient chain transfer agentsfor methyl methacrylate and that the process produces polymers of lowmolecular weight in a controlled manner. A sample of poly(methylmethacrylate) produced similarly using 392 mg of the mixture wasprecipitated two further times from ethyl acetate/pentane to removetraces of the unreacted chain transfer agent. The resulting polymer ofnumber-average molecular weight 4414 had signals at δ0.12 in the ¹H NMRspectrum confirming the presence of the tert-butyldimethylsilyloxygroup. Such a group can be readily converted by well-known methods (suchas stirring with tetrabutylammonium fluoride in a solvent) to a hydroxylgroup.

Example 79

Preparation of Low Molecular Weight Hydroxy-Terminated Polymers ofMethyl Methacrylate Using α-Benzyloxy[4-(hydroxymethyl)styrene] andM-Benzyloxy[3-(hydroxymethyl)styrene]

(Formula II, R¹ HOCH₂C₆H₄—, R²=benzyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 10.8 mg, and 20.1 mg of a mixture ofα-benzyloxy[4-(hydroxymethyl)styrene] andα-benzyloxy[3-(hydroxymethyl)styrene] had number-average molecularweights of 182396, 110353, and 41759, respectively. The chain transferconstant calculated from these data was 0.41 These results show that thecompounds act as efficient chain transfer agents for methyl methacrylateand that the process produces hydroxy-terminated polymers of lowmolecular weight. A sample of poly(methyl methacrylate) producedsimilarly using 345 mg of the mixture was precipitated two further timesfrom ethyl acetate/pentane to remove traces of the unreacted chaintransfer agent. The resulting polymer of number-average molecular weight10975 had signals between δ 4.5 and 4.7 in the ¹R NMR spectrumconfirming the presence of a hydroxymethylphenyl group.

Example 80

Preparation of Low Molecular Weight Acetoxy-Terminated Polymers ofStyrene Using α-Benzyloxy(4-(acetoxymethyl)styrene] andα-Benzyloxy[3-(acetoxymethyl)styrene]

(Formula II, R¹=CH₃CO₂CH₂C₆H₄—, R₂=benzyl).

Samples of polystyrene prepared in the manner of example 48 using 100.2mg, 151.6 mg, and 198.6 mg of a mixture ofα-benzyloxy[4-(acetoxymethyl)styrene] andα-benzyloxy[3-(acetoxymethyl)styrene] had number-average molecularweights of 48465, 38481, and 31175, respectively. The chain transferconstant calculated from these data was 0.33. These results show thatthe mixture acts as an efficient chain transfer agent for styrene andthat the process produces acetoxy-terminated polymers of low molecularweight in a controlled manner. A sample of polystyrene preparedsimilarly using 2 g of the mixture was precipitated two further timesfrom ethyl acetate/methanol to remove traces of the unreacted chaintransfer agent. The resulting polymer of number-average molecular weight7673 had signals at δ 5.06 in the ¹H NMR spectrum confirming thepresence of an (acetoxymethyl)phenyl group. Integration of the spectrumshowed that one of these groups was present per polymer chain. Theinfrared spectrum of the polymer showed an absorption at 1740 cm⁻¹ alsoconfirming the presence of the ester group. This group could be readilyhydrolysed to an OH group.

Example 81

Preparation of Low Molecular Weight Chlorophenyl-Terminated Polymers ofMethyl Methacrylate Using α-Benzyloxy(4-chlorostyrene)

(Formula II, R¹=4-chlorophenyl, R²=benzyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 22.8 mg and 49.1 mg of α-benzyloxy(4-chlorostyrene) hadnumber-average molecular weights of 25000, and 11900 respectively. Thechain transfer constant calculated from these data was 0.75. Theseresults show that α-benzyloxy(4-chlorostyrene) acts as an efficientchain transfer agent for methyl methacrylate and that the processproduces chlorophenyl-terminated polymers of low molecular weight in acontrolled manner.

Example 82

Preparation of Low Molecular Weight Methoxy-Terminated Polymers ofMethyl Methacrylate Using α-Benzyloxy(3-methoxystyrene)

(Formula II, R¹=3-CH₃OC₆H₄—, R²=benzyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 24.8 mg and 40.2 mg of α-benzyloxy(3-methoxystyrene) hadnumber-average molecular weights of 20423 and 12707, respectively. Thechain transfer constant calculated from these data was 0.83. Theseresults show that α-benzyloxy(3-methoxystyrene) acts as an efficientchain transfer agent for methyl methacrylate and that the processproduces methoxy-terminated polymers of low molecular weight in acontrolled manner.

Example 83

Preparation of Low Molecular Weight Methoxy-Terminated Polymers ofMethyl Methacrylate Using α-Benzyloxy(4-methoxystyrene)

(Formula II, R¹=4-CH₃OC₆H₄—, R²=benzyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 20.7 mg and 44.7 mg of α-benzyloxy(4-methoxystyrene) hadnumber-average molecular weights of 38931 and 19947, respectively. Thechain transfer constant calculated from these data was 0.46. Theseresults show that α-benzyloxy(4-methoxystyrene) acts as an efficientchain transfer agent for methyl methacrylate and that the processproduces methoxy-terminated polymers of low molecular weight in acontrolled manner.

Example 84

Preparation of Low Molecular Weight α-Acetoxy, ω-MethoxycarbonylPolystyrene Usingα-(4-Methoxycarbonylbenzyloxy)[4-(acetoxymethyl)styrene] andα-(4-Methoxycarbonylbenzyloxy)[3-(acetoxymethyl)styrene]

(Formula II, R¹=CH₃CO₂CH₂C₆H₄—, R²=C₃OC(O)CH₂C₆H₄CH₂—).

Samples of polystyrene prepared in the manner of example 48 using 0 mg,40.0 mg, 80.4 mg, and 160.0 mg of a mixture ofα-(4-methoxycarbonylbenzyloxy)[4-(acetoxymethyl)styrene] andα-(4-methoxycarbonylbenzyloxy)[3-(acetoxymethyl)styrene] hadnumber-average molecular weights of 120702, 97477, 78326, and 57711,respectively. The chain transfer constant calculated from these data was0.18. These results show that the mixture acts as an efficient chaintransfer agent for styrene and that the process producesbis-end-functional polymers of low molecular weight in a controlledmanner. A sample of polystyrene produced similarly using 966 mg of themixture was precipitated two further times from ethyl acetate/methanolto remove traces of the unreacted chain transfer agents. The resultingpolymer of number-average molecular weight 10873 had signals at 6 3.82and 5.05 in the ¹H NMR spectrum confirming the presence of methyl estergroups and acetoxymethyl groups. Integration of the spectrum showed thatone of each of these groups was present per polymer chain. The infraredspectrum of the polymer showed absorptions at 1720 and 1740 cm⁻¹ alsoconfirming the presence of the ester groups. The resultant polymer couldbe readily hydrolysed by methods well known to the art to give a polymerterminated at one end with a hydroxyl group and terminated at the otherend by a carboxylic acid moiety.

Example 85

Preparation of Low Molecular Weight α,ω-Dihydroxypoly(methylmethacrylate) Usingα-[4-(Hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] andα-[4-(Hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene]

(Formula II, R¹=HOCH₂C₆H₄—, R²=HOCH₂C₆H₄CH₂—).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 10.1 mg, 18.9 mg, and 42.7 mg of a mixture ofα-[4-(hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] andα-[4-(hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene] hadnumber-average molecular weights of 173410, 42227, 26264, and 15222,respectively. The chain transfer constant calculated from these data was0.73. These results show that the compounds act as an efficient chaintransfer agent for methyl methacrylate and that the process producesbis-hydroxy end-functional polymers of low molecular weight in acontrolled manner. A sample of poly(methyl methacrylate) producedsimilarly using 374 mg of the mixture was precipitated one further timefrom ethyl acetate/pentane and three times from ethyl acetate/methanolremove traces of the unreacted chain transfer agent. The resultingpolymer of number-average molecular weight 36422 had signals at δ4.5-4.7in the ¹H NMR spectrum confirming the presence of hydroxymethylphenylgroups. The infrared spectrum of the polymer showed a broad absorptionat 3505 cm⁻¹ confirming the presence of the hydroxyl groups.

Example 86

Preparation of Low Molecular Weight α,ω-Dihydroxypolystyrene Usingα-[4-(Hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] andα-[4-(Hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene]

(Formula II, R¹=HOCH₂C₆H₄—, R=HOCH₂C₆H₄CH₂—).

A sample of polystyrene produced in the manner of example 48 using 1.9 gof a mixture ofα-[4-(hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene]andα-[4-(hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene] wasprecipitated three times from ethyl acetate/methanol to remove traces ofthe unreacted chain transfer agents. The resulting bis-end-functionalpolymer of number-average molecular weight 8942 had signals at δ 4.4-4.7in the ¹H NMR spectrum confirming the presence of hydroxymethylphenylgroups.

Example 87

Preparation of Low Molecular Weightα,ω-bis(t-Butyldimethylsilyloxymethyl)poly(methyl methacrylate) Usingα-[4-(t-butyldimethylsilyloxymethyl)benzyloxy][4-(t-butyldimethylsilyloxymethyl)styrene]andα-[4-(t-butyldimethylsilyloxymethyl)benzyloxy][3-(t-butyldimethylsilyloxymethyl)styrene]

(Formula II, R¹=(t-butyldimethylsilyloxymethyl)phenyl,R²=4-(t-butyldimethylsilyloxymethyl)benzyl).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, 34.3 mg, 70.1 mg, and 97.5 mg of a mixture ofα-[4-(t-butyldimethylsilyloxymethyl)benzyloxy][4-(t-butyldimethylsilyloxymethyl)styrene] andα-[4-(t-butyldimethylsilyloxymethyl)benzyloxy][3-(t-butyldimethylsilyloxymethyl)styrene]had number-average molecular weights of 227540, 32925, 18286, and 14520,respectively. The chain transfer constant calculated from these data was0.65. These results show that these compounds act as an efficient chaintransfer agent for methyl methacrylate and that the process producesbis-silyloxy end-functional polymers of low molecular weight in acontrolled manner. A sample of poly(methyl methacrylate) producedsimilarly using 369 mg of the mixture was precipitated two further timesfrom ethyl acetate/pentane to remove traces of the unreacted chaintransfer agent. The resulting polymer of number-average molecular weight5907 had signals at δ 0.0-0.14 and 4.6-4.8 in the ¹H NMR spectrumconfirming the presence of the t-butyldimethylsilyloxymethylphenylgroups. Integration of the spectrum showed that two of these groups werepresent per polymer chain.

Example 88

Preparation of Low Molecular Weight α-Hydroxy-, w-Amino Poly(methylmethacrylate) Usingα-[4-(Hydroxymethyl)benzyloxy][4-(aminomethyl)styrene]

(Formula II, R¹=H₂NCH₂C₆H₄—, R²=HOCH₂C₆H₄CH₂—).

Samples of poly(methyl methacrylate) prepared in the manner of example47 using 0 mg, and 31.0 mg ofα-[4-(hydroxymethyl)benzyloxy][4-(aminomethyl)styrene]had number-averagemolecular weights of 236538, and 24233, respectively. The chain transferconstant calculated from these data was 0.6. These results show thatα-[4-(hydroxymethyl)benzyloxy]-[(aminomethyl)styrene] acts as anefficient chain transfer agent for methyl methacrylate and that theprocess produces polymers of low molecular weight terminated by an aminogroup and a hydroxyl group.

Example 89

Preparation of Low Molecular Weight Polyacrylonitrile Usingα-Benzyloxystyrene

(Formula II, R¹=phenyl, R²=benzyl).

Azobisisobutyronitrile (7.4 mg) was dissolved in freshly distilledacrylonitrile (10 ml). An aliquot (2 ml) was removed and added toα-benzyloxystyrene (18.5 mg) and the mixture was polymerized in theabsence of oxygen for 1 h at 60° C. The resulting polymer wasprecipitated in toluene. A portion (100 mg) of the dried polymer wasdissolved in dimethylformamide (10 ml) and the viscosity was measuredusing a Gardiner Bubble viscometer. The resulting polymer had aviscosity less than that of tube B. A similar polymer prepared withoutadded chain transfer agent had a viscosity equal to that of tube E. Thisresult shows that the polymer prepared using α-benzyloxystyrene had alower molecular weight than that prepared without, and thatα-benzyloxystyrene acts as a chain transfer agent for acrylonitrile.

What is claimed is:
 1. An improved process for the production of polymeror oligomer of controllably reduced molecular weight by the/free radicalpolymerization of monomers in the presence of an initiator and a chaintransfer agent which is present in an effective amount to control themolecular weight of said polymer or oligomer: wherein said chaintransfer agent terminates the growth of the polymer chain by addition tothe propagating polymer radical followed by expulsion of a radical whichthen initiates another polymer chain; wherein the improvement comprisesemploying a chain transfer agent having the formula

wherein R¹ is selected from the group consisting of cyano, carboxyl,optionally substituted alkoxycarbonyl, and phenyl substituted with asubstituent selected from the group consisting of hydroxyl, carboxyl,amino, epoxy, and halogen; R², excluding oxetane, is C₁-C₃₂-alkyl,C₂-C₃₂-alkenyl, C₂-C₃₂-alkynyl, or saturated, unsaturated or aromaticcarbocyclic 3 to 14 atom ring, said R² being optionally substituted witha reactive or a non-reactive substituent, said reactive substituentbeing selected from the group consisting of hydroxy, amino, halogen,phosphonate, trialkylsilyl, allyl, cyano, epoxy, carboxylic acid, andcarboxylic acid ester, said non reactive substituent being selected fromthe group consisting of alkoxy and alkyl.
 2. An improved process for theproduction of polymer or oligomer of controllably reduced molecularweight by the free radical polymerization of monomers in the presence ofan initiator and a chain transfer agent which is present in an effectiveamount to control the molecular weight of said polymer or oligomer:wherein said chain transfer agent terminates the growth of the polymerchain by addition to the propagating polymer radical followed byexpulsion of a radical which then initiates another polymer chain;wherein the improvement comprises employing a chain transfer agenthaving the formula:

wherein R¹ is selected from the group consisting of cyano, carboxyl,optionally substituted alkoxycarbonyl, and phenyl substituted with asubstituent selected from the group consisting of hydroxyl, carboxyl,amino, epoxy, and halogen; R², excluding oxetane, is methyl substitutedwith one or more groups selected from phenyl or other aromatic group andalkyl; said phenyl And other aromatic group and alkyl being optionallysubstituted with a reactive substituent selected from the groupconsisting of halogen, cyano, epoxy, hydroxy, amino, carboxy,alkoxycarbonyl, aryloxycarbonyl, carbamoyl, acyloxy, trialkylsilyloxy,trialkoxysilyl, phosphonate and alkenyl.